Global glossary
Glossary index
Canonical definitions and concise technical references for terms, quantities, devices, laws, models, and methods. Browse by initial letter or by canonical engineering discipline; each term is stored once and linked to its primary branch.
Alphabet · A–Z
Organized by discipline
13 Aerospace Engineering 27 Automation and Control Engineering 10 Biomedical Engineering 10 Chemical Engineering 11 Civil and Construction Engineering 35 Electrical Engineering 24 Electronic Engineering 10 Engineering Physics 10 Environmental Engineering 11 Industrial and Management Engineering 14 Computer Engineering 29 Mathematical Engineering 44 Materials Engineering 54 Mechanical Engineering 10 Mining and Georesources Engineering 10 Naval and Marine Engineering 10 Telecommunications Engineering 20 Energy Engineering
08 latest · 13 total
Open branch Aerospace Engineering
- A-Z Thrust Thrust is the propulsive force produced when a system accelerates mass or exchanges momentum with a surrounding fluid.
- A-Z Vortex Shedding Vortex shedding is the periodic formation and release of alternating vortices behind a bluff body in a fluid flow.
- A-Z Wake A wake is the region of disturbed, slower, and often vortical flow downstream of a body immersed in or moving through a fluid.
- A-Z Wind Tunnel A wind tunnel is a test facility that produces controlled airflow around models, vehicles, components, or specimens to measure aerodynamic behavior.
- A-Z Xenon Ion Thruster A xenon ion thruster is an electric spacecraft propulsion device that ionizes xenon and accelerates the ions through electric fields to generate thrust.
- A-Z Yaw Angle Yaw angle is the angular orientation of a vehicle or body about its vertical or body-z axis relative to a specified reference direction.
- A-Z Yaw Rate Yaw rate is the angular velocity of a vehicle or body about its vertical or body-z axis, usually measured by inertial sensors or estimated in motion models.
- A-Z Aerodynamic Drag The resistive force exerted by air or another gas on a body moving relative to the flow.
08 latest · 27 total
Open branch Automation and Control Engineering
- A-Z Root Locus Root locus is a graphical control-design method that shows how closed-loop poles move in the complex plane as a gain or parameter changes.
- A-Z Sensitivity Function The sensitivity function is the closed-loop transfer function from a disturbance (or reference) to the tracking error, quantifying how effectively the feedback loop rejects disturbances at each frequency.
- A-Z Stability Margin A stability margin is a quantitative measure of the distance between the operating point of a feedback control system and the boundary of instability, expressed in terms of allowable gain increase (gain margin) or allowable phase lag (phase margin).
- A-Z State-Space Model A state-space model represents a dynamic system through state variables, inputs, outputs, and equations that describe how the state evolves over time.
- A-Z Time Constant A time constant is the characteristic time scale of a first-order exponential response, indicating how fast a system approaches a new steady state.
- A-Z Transfer Function A transfer function is the ratio of the Laplace transform of a system's output to the Laplace transform of its input, assuming zero initial conditions, and provides a complete description of the input–output behaviour of a linear time-invariant system.
- A-Z Zero-Order Hold A zero-order hold is a sampled-data model or circuit behaviour in which each sample value is held constant until the next sample is available.
- A-Z Ziegler-Nichols Method The Ziegler-Nichols method is an empirical approach for choosing PID controller gains from either an open-loop process reaction curve or the ultimate closed-loop gain and oscillation period.
08 latest · 10 total
Open branch Biomedical Engineering
- A-Z Biocompatibility Biocompatibility is the ability of a material, device, or surface to perform with an acceptable biological response for a defined medical use.
- A-Z Biomechanics Biomechanics applies mechanics to living tissues, movement, implants, medical devices, and body-machine interfaces.
- A-Z Biosignal A biosignal is a measurable signal produced by a living system or by its interaction with a sensor.
- A-Z Clinical Engineering Clinical engineering applies engineering methods to the safe and effective management of medical technology in healthcare environments.
- A-Z Diagnostic Imaging Diagnostic imaging is the use of engineered systems to form visual or quantitative evidence about internal structure, function, or condition.
- A-Z Medical Device A medical device is an engineered product or system intended to support diagnosis, monitoring, treatment, compensation, prevention, or clinical workflow.
- A-Z Patient Safety Patient safety is the engineering and clinical outcome of reducing avoidable harm to patients during diagnosis, monitoring, treatment, support, or care delivery.
- A-Z Physiological Monitoring Physiological monitoring is the measurement and interpretation of biological or patient signals over time.
08 latest · 10 total
Open branch Chemical Engineering
- A-Z Heat Duty Heat duty is the rate of heat transfer required, supplied, removed, recovered, or rejected across a defined boundary.
- A-Z Reaction Rate Reaction rate is the rate at which a chemical species is consumed or produced by reaction.
- A-Z Rheology Rheology is the study of how materials flow, yield, relax, and deform under applied stress or strain.
- A-Z UV Curing UV curing is a manufacturing process in which ultraviolet radiation triggers photochemical reactions that polymerize, crosslink, or harden a material.
- A-Z Valve Coefficient Valve coefficient is a flow-capacity rating that relates valve opening, pressure drop, fluid properties, and flow rate under defined reference conditions.
- A-Z Vapor Pressure Vapor pressure is the equilibrium pressure of a vapor in contact with its liquid or solid phase at a specified temperature.
- A-Z Zeta Potential Zeta potential is the electrokinetic potential associated with the slipping plane around a particle, droplet, or interface moving through a liquid.
- A-Z Chemical Reactor A vessel or system designed to carry out a chemical reaction under controlled conditions of flow, temperature, pressure, composition, mixing, and residence time.
08 latest · 11 total
Open branch Civil and Construction Engineering
- A-Z Retaining Wall A retaining wall is a civil structure that holds back soil, rock, water, or granular fill where a stable natural slope cannot be used.
- A-Z Allowable Stress The maximum stress permitted in a component or structure under a specified design basis after applying safety factors, code limits, and service conditions.
- A-Z Beam Deflection The displacement or rotation of a beam from its unloaded geometry under loads, support conditions, temperature effects, or imposed movement.
- A-Z Deflection The displacement or rotation of a structural or mechanical element from its original position under load, temperature change, support movement, or imposed deformation.
- A-Z Design Load The load value or load effect used for design after applying the governing combinations, factors, service conditions, and code requirements.
- A-Z Euler Buckling Euler buckling is the ideal elastic stability model that estimates the critical axial compressive load at which a perfectly straight slender column buckles laterally.
- A-Z Excavation Support A temporary or permanent system used to stabilize soil, rock, groundwater, and adjacent structures around an excavation.
- A-Z Green Building Green building is the integrated design, construction, and operation of buildings to reduce environmental impact while preserving health, comfort, resilience, and lifecycle performance.
08 latest · 35 total
Open branch Electrical Engineering
- A-Z Fault Detection Fault detection is the process of identifying abnormal conditions or faults from measurements, events, models, inspections, or diagnostic evidence.
- A-Z Grid-Forming Inverter A grid-forming inverter is an inverter capability that can establish and regulate voltage and frequency for an islanded or weak electric grid.
- A-Z Uninterruptible Power Supply An uninterruptible power supply is a power system that keeps a load energized during short input disturbances, voltage problems, or outages.
- A-Z Reactive Power Reactive power is the component of apparent power in an AC circuit that oscillates between the source and reactive elements — inductors and capacitors — without being converted into useful work or heat, representing energy temporarily stored in magnetic or electric fields.
- A-Z Relay An electrically operated switching device used for control, protection, or isolation.
- A-Z Surge Impedance Surge impedance is the characteristic impedance seen by a travelling electromagnetic wave on a line before reflections from terminations return.
- A-Z Thevenin Equivalent A Thevenin equivalent represents a linear two-terminal network as an ideal voltage source in series with an equivalent impedance.
- A-Z Vector Control Vector control is a motor-control method that transforms measured phase quantities into rotating reference-frame components so flux-producing and torque-producing currents can be controlled independently.
08 latest · 24 total
Open branch Electronic Engineering
- A-Z Semiconductor A semiconductor is a material with controllable electrical conductivity between that of a conductor and an insulator.
- A-Z Solder Joint A solder joint is a metallurgical connection that bonds component terminations to pads, wires, or terminals while providing electrical and mechanical continuity.
- A-Z Thermocouple A thermocouple is a temperature sensor that uses the Seebeck voltage generated by two dissimilar conductors joined at a measurement junction.
- A-Z Transducer A transducer is a device that converts a physical quantity or form of energy into another signal form, usually for measurement, control, or actuation.
- A-Z Voltage Regulator A voltage regulator is a circuit or device that keeps an output voltage within specified limits despite changes in input voltage, load current, and temperature.
- A-Z X-Ray Lithography X-ray lithography is a microfabrication process that patterns a resist layer by exposing it through a mask with short-wavelength X-rays.
- A-Z Xenon Arc Lamp A xenon arc lamp is a gas-discharge light source in which an electric arc through xenon gas produces intense broadband radiation.
- A-Z Zener Diode A Zener diode is a diode intended to conduct in reverse breakdown at a specified voltage while maintaining a relatively controlled voltage across its terminals.
08 latest · 10 total
Open branch Engineering Physics
- A-Z Diffraction Diffraction is wave spreading and interference caused by apertures, edges, periodic structures, or features comparable to wavelength.
- A-Z Electromagnetic Wave An electromagnetic wave is a propagating disturbance of coupled electric and magnetic fields.
- A-Z Mean Free Path Mean free path is the average distance a particle or molecule travels between collisions or interactions.
- A-Z Optical Power Optical power is the rate at which light energy crosses a defined optical boundary.
- A-Z Plasma Plasma is an ionized gas containing free electrons, ions, neutral particles, and electromagnetic fields.
- A-Z Radiation Dose Radiation dose describes how much ionizing radiation energy is deposited in material or tissue.
- A-Z Scattering Scattering is the redistribution of waves, particles, or radiation when they interact with matter, geometry, defects, or boundaries.
- A-Z Seebeck Effect The Seebeck effect is the generation of an electromotive force when a temperature difference exists along a conductor, semiconductor, or thermoelectric junction.
08 latest · 10 total
Open branch Environmental Engineering
- A-Z Air Emissions Air emissions are pollutants, vapors, particles, gases, odors, or heat released to the atmosphere from a defined source or boundary.
- A-Z Contaminant Transport Contaminant transport is the movement, spreading, retention, and transformation of contaminants through environmental or engineered media.
- A-Z Environmental Compliance Environmental compliance is the controlled operating state in which emissions, discharges, waste, monitoring, evidence, and reporting satisfy applicable environmental requirements.
- A-Z Environmental Monitoring Environmental monitoring is the planned measurement of environmental conditions, emissions, discharges, contaminants, or control-system performance.
- A-Z Groundwater Remediation Groundwater remediation is the engineered containment, removal, treatment, transformation, or monitoring of contaminated groundwater.
- A-Z Pollutant Load Pollutant load is the mass of a pollutant entering, leaving, generated in, or removed from a system over a defined basis.
- A-Z Stormwater Runoff Stormwater runoff is rainfall or snowmelt that flows over surfaces or through drainage systems rather than infiltrating, evaporating, or being stored locally.
- A-Z Wastewater Treatment Wastewater treatment is the engineered removal, transformation, or control of contaminants in wastewater before discharge, reuse, or further handling.
08 latest · 11 total
Open branch Industrial and Management Engineering
- A-Z Reliability The probability that a system performs its required function for a specified time under stated conditions.
- A-Z Risk Priority Number Risk Priority Number is a prioritisation score used in FMEA, typically calculated from severity, occurrence, and detection rankings.
- A-Z Unit Load A unit load is a standardized amount of material, goods, or load treated as a single handling, storage, transport, or design unit.
- A-Z Usability Engineering Usability engineering is the systematic design and evaluation of systems so intended users can perform intended tasks effectively, efficiently, and safely in context.
- A-Z Validation Validation is the process of confirming that a model, product, process, or system is suitable for its intended use in its intended context.
- A-Z Work Breakdown Structure A work breakdown structure is a hierarchical decomposition of project scope into deliverables, work packages, and manageable units of work.
- A-Z Critical Path Method A project scheduling method that identifies the longest dependency path through planned activities and therefore the sequence controlling project duration.
- A-Z Failure Mode A specific way in which a component, process, or system can fail to perform its intended function.
08 latest · 14 total
Open branch Computer Engineering
- A-Z Machine Learning Machine learning is a family of computational methods that learn patterns, predictions, or decision rules from data.
- A-Z XHTML XHTML is an XML-based form of HTML that represents web documents with strict, well-formed markup.
- A-Z XOR Gate An XOR gate is a digital logic gate that outputs logic 1 when its inputs differ and logic 0 when they are the same.
- A-Z Aliasing The distortion that occurs when a signal is sampled too slowly or without sufficient filtering, causing high-frequency content to appear as false lower-frequency content.
- A-Z Binary Tree A hierarchical data structure in which each node has at most two child nodes, commonly called the left and right child.
- A-Z Boolean Algebra The algebra of two-valued logic used to represent, simplify, and verify logical operations in digital and computational systems.
- A-Z Data Bus A shared communication pathway that transfers data between components, subsystems, or devices in a digital or embedded system.
- A-Z Digital Twin A digital representation of a physical asset, process, or system that is updated with operational data to support analysis, prediction, control, or decision-making.
08 latest · 29 total
Open branch Mathematical Engineering
- A-Z Uncertainty Analysis Uncertainty analysis evaluates how imperfect knowledge of inputs, measurements, assumptions, or models affects a calculated result or decision.
- A-Z Weibull Distribution The Weibull distribution is a flexible probability distribution used to model time-to-failure, strength, fatigue life, and weakest-link behavior.
- A-Z X-Axis The x-axis is a chosen reference direction in a coordinate system, usually used as the first coordinate for position, geometry, data, or state variables.
- A-Z Y-Axis The y-axis is the second reference axis of a coordinate system, often perpendicular to the x-axis and used to locate position, plot variables, or define model directions.
- A-Z Z-Axis The z-axis is the third reference axis in a three-dimensional coordinate system, usually used to describe depth, height, thickness, or out-of-plane direction.
- A-Z Z-Score A z-score is a dimensionless standardized value equal to the distance between an observation and a reference mean divided by the reference standard deviation.
- A-Z Z-Transform The z-transform maps a discrete-time sequence into a complex-domain function for analysing sampled signals and systems.
- A-Z Boundary Condition A constraint imposed on the boundary of a model domain to make a physical or mathematical problem well defined.
08 latest · 44 total
Open branch Materials Engineering
- A-Z S–N Curve The S–N curve is a graphical representation of the relationship between the applied cyclic stress amplitude S and the number of cycles to failure N for a material tested under controlled fatigue loading conditions.
- A-Z Shear Modulus Shear modulus is the elastic stiffness that relates shear stress to shear strain in the linear elastic range.
- A-Z Tensile Strength Tensile strength is the tensile stress level associated with fracture or with the maximum load carried during a tensile test, depending on the material and reporting convention.
- A-Z Ultimate Tensile Strength Ultimate tensile strength is the maximum engineering tensile stress recorded during a uniaxial tensile test.
- A-Z Ultrasonic Testing Ultrasonic testing is a non-destructive inspection method that uses high-frequency mechanical waves to detect flaws, measure thickness, or characterize material condition.
- A-Z Universal Testing Machine A universal testing machine is a calibrated test frame used to apply controlled tensile, compressive, bending, peel, or shear loads to specimens.
- A-Z Weld Bead A weld bead is the deposited and solidified weld metal produced by one welding pass or by the visible surface of a weld.
- A-Z Work Hardening Work hardening is the increase in strength and hardness that occurs when a ductile material is plastically deformed.
08 latest · 54 total
Open branch Mechanical Engineering
- A-Z Resonance Large-amplitude response that occurs when excitation frequency is near a natural frequency.
- A-Z Reynolds Number The Reynolds number is a dimensionless ratio of inertial forces to viscous forces in a fluid flow.
- A-Z Rotor Dynamics Rotor dynamics is the study of vibration, stability, and dynamic forces in shafts, disks, bearings, seals, and other rotating machinery.
- A-Z Runout Runout is the measured deviation of a rotating surface or feature from ideal circular, coaxial, or axial alignment relative to a datum.
- A-Z Screw Thread A screw thread is a helical ridge on a cylindrical or conical surface used for fastening, adjustment, sealing, or converting rotation into linear motion.
- A-Z Strain Gauge A strain gauge is a sensor that converts mechanical strain into a small change in electrical resistance.
- A-Z Stress Stress is the internal force per unit area that develops inside a material when it is subjected to external loads, displacements, or thermal effects.
- A-Z Stress Concentration Stress concentration is the local amplification of stress that occurs in the vicinity of geometric discontinuities — holes, notches, fillets, grooves, threads, keyways, or weld toes — where the smooth flow of internal forces is disrupted.
08 latest · 10 total
Open branch Mining and Georesources Engineering
- A-Z Georesource Model A georesource model is an engineering representation of a deposit or subsurface resource used for planning, design, and risk decisions.
- A-Z Grade Control Grade control is the operational process of estimating, classifying, and routing mined material to manage ore quality, dilution, recovery, and value.
- A-Z Mine Closure Mine closure is the planned transition from active mining to stable, safe, environmentally controlled, and monitored post-mining conditions.
- A-Z Mine Dewatering Mine dewatering is the engineered removal and control of water that affects mine access, stability, production, and environmental performance.
- A-Z Mine Reclamation Mine reclamation is the engineering and operational process of stabilizing, restoring, repurposing, or safely closing land affected by mining.
- A-Z Mine Ventilation Mine ventilation is the engineered movement and control of air through mine workings to manage breathing air, contaminants, heat, and emergency conditions.
- A-Z Ore Grade Ore grade is the concentration of a valuable mineral, metal, or component in mined material.
- A-Z Rock Mass Rating Rock mass rating is a geotechnical classification method used to summarize rock mass quality for excavation, slope, and support decisions.
08 latest · 10 total
Open branch Telecommunications Engineering
- A-Z Sampling Theorem The sampling theorem states that an ideal band-limited signal can be reconstructed exactly from uniformly spaced samples when the sampling frequency is greater than twice the signal bandwidth.
- A-Z Signal-to-Noise Ratio Signal-to-noise ratio is the ratio between desired signal power and noise power over a specified bandwidth and measurement condition.
- A-Z Uplink Budget An uplink budget is a power and noise accounting model for the transmission path from a user or ground transmitter to a satellite, base station, or network receiver.
- A-Z Waveguide A waveguide is a physical structure that confines and guides electromagnetic, optical, or acoustic waves along a desired path.
- A-Z X-Band Radar X-band radar is a radar system that operates in the microwave X band, roughly 8 to 12 GHz, to detect, range, track, or image targets.
- A-Z Yagi-Uda Antenna A Yagi-Uda antenna is a directional antenna made from a driven element, a reflector, and one or more parasitic director elements.
- A-Z Bandwidth The frequency range over which a signal, channel, instrument, or control system can transmit or respond with acceptable performance.
- A-Z Jitter Jitter is short-term deviation in the timing of signal transitions, samples, packets, or clock events from their ideal time positions.
08 latest · 20 total
Open branch Energy Engineering
- A-Z Battery Energy Storage System A battery energy storage system is an electrical energy storage system that uses batteries with power conversion, controls, protection, and thermal management.
- A-Z Demand Response Demand response is the controlled change of electricity consumption in response to grid needs, prices, control signals, or emergencies.
- A-Z Depth of Discharge Depth of discharge is the fraction of a battery's rated or reference capacity that has been removed during discharge.
- A-Z Liquid Cooling Liquid cooling is a thermal management method that removes heat by transferring it into a circulating or contained liquid.
- A-Z Microgrid A microgrid is a local electric power system with defined electrical boundaries and coordinated control that can operate connected to the main grid or, if designed for it, in islanded mode.
- A-Z Power Usage Effectiveness Power usage effectiveness is a data center efficiency metric equal to total facility power divided by IT equipment power.
- A-Z Rack Power Density Rack power density is the electrical power assigned to or consumed by a data center rack, commonly expressed in kilowatts per rack.
- A-Z Round-Trip Efficiency Round-trip efficiency is the ratio of energy delivered by an energy storage system to the energy required to charge it over a defined cycle and boundary.