In electrical engineering, an armature is the component of an electric machine which carries alternating current.

The Argonaut class reactor is a design of small nuclear research reactor. Its functions are to teach nuclear reactor theory, nuclear physics and for use in engineering laboratory experiments.

The subject area an individual, team or company that has demonstrated competency.

An electric arc may form between power system conductors and ground where the system voltage is high enough.

An arch-gravity dam is a dam with the characteristics of both an arch dam and a gravity dam.

An arch dam is a concrete dam that is curved upstream in plan. The arch dam is designed so that the force of the water against it, known as hydrostatic pressure, presses against the arch, causing the arch to straighten slightly and strengthening the structure as it pushes into its foundation or abutments.

An arc-fault circuit interrupter is a circuit breaker that breaks the circuit when it detects the electric arcs that are a signature of loose connections in home wiring.

Arc suppression is the reduction of sparks formed when current-carrying contacts are separated.

An arc lamp or arc light is a lamp that produces light by an electric arc.

A method of seasonal thermal energy storage that utilises underground aquifers.

An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials.

Aqueous homogeneous reactors are a type of nuclear reactor in which soluble nuclear salts (usually uranium sulfate or uranium nitrate) are dissolved in water.

The Appropriate Infrastructure Development Group provided access to environmentally friendly infrastructure in impoverished communities in developing countries through a combination of business incubation, education, and direct outreach.

Applied engineering education is defined as a program that generally prepares individuals to apply mathematical and scientific principles inherent to engineering to the management and design of systems, execution of new product designs, improvement of manufacturing processes, and the management and direction of the physical or technical functions of an organization.

The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water: if its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks.

Hydrocarbon cracking is the process of breaking a long chain of hydrocarbons into short ones.

Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some chemical, between two flowing bodies flowing in opposite directions to each other.

Counter-electromotive force also known as back electromotive force, is the electromotive force or "voltage" that opposes the change in current which induced it.

A fixed bed of carbonaceous fuel (e.g. coal or biomass) through which the "gasification agent" (steam, oxygen and/or air) flows in counter-current configuration.

The coulomb is the International System of Units (SI) unit of electric charge.