Architectural and Engineering Glossary


Absorption Field, Disposal Field

 A system of trenches containing coarse aggregate and distribution pipes through which septic tank effluent may seep into the surrounding soil.

Absorption Rate,initial Rate Of Absorption

The weight of water absorbed when a brick is partially immersed for one minute; usually expressed in grams per minute or ounces per minute.

Absorption System

A refrigeration system in which the refrigerant gas evolved in the evaporator is taken up in an absorber and (upon the application of heat) released in a generator.

Absorption Trench

 A trench containing coarse aggregate and a distribution tile pipe through which septic-tank effluent may flow, covered with earth.

Absorption-type Liquid Chiller

 Equipment utilizing a generator, condenser, absorber, evaporator, pumps, controls, and accessories to cool water, or other secondary liquid, using absorption techniques.

Abstract Of Title

 An outline history of the ownership of a parcel of land, from the original grant, with changes in title, and with a statement of all mortgages, liens, encumbrances, etc., affecting the property.


 A masonry mass (or the like) which receives the thrust of an arch, vault, or strut.


 Those boundaries of one piece of land that abut on adjacent pieces.

Abutting Joint

 A joint between two pieces of wood, in which the direction of the grain in one piece is at an angle (usually 90) to the grain in the other.

Abutting Tenon

One of two tenons which are inserted in a common mortise from opposite sides, so as to touch each other.

AC Generator

 A generator which produces alternating current when driven by a prime mover.


 A common plant of the Mediter- ranean, whose leaves, stylized, form the charac- teristic decoration of capitals of Corinthian and Composite orders. In scroll form it appears on friezes, panels, etc.


1.Abbr. for asbestos-cement board.2.Abbr. for “air circuit breaker.”

Accelerated Aging

 The speeding-up of the aging process in a material; obtaining, in a short time, the results that would occur in aging under normal conditions. The most common factors that increase aging include exposure of the material to water, ozone, oxygen, or sun- light.

Accelerated Life Test

 A test in which one or more parameters (e.g., temperature) is increased or decreased beyond its normal or rated value to determine the resulting deterioration within a reasonable time period.

Accelerated Weathering

 A laboratory testing technique to determine, in a relatively short time, the weather resistance of a paint film or other exposed surface.

Accelerating Admixture

 An admixture that speeds the setting and/or the early strength development of hydraulic concrete.


 1.The rate of change of the velocity of a moving body. 2.The rate of change, esp. the quickening of the natural progress of a process, such as hardening, setting, or strength development of concrete.

Acceleration Of Gravity (g)

The acceleration produced by the force of gravity at the surface of the earth. (By international agreement the value ofgis 386.089 inches per second square  32.1740 feet per second square 9.80665 meters per second square.)

Acceleration Stress

 In a wire rope (or the like), the additional stress imposed as a result of the acceleration of the load.


 1.A substance which, when added to concrete, mortar, or grout, increases the rate of hydration of a hydraulic cement, shortens the time of set, or increases the rate of hardening or strength development. 2.A substance, added with a curing agent, to speed a vulcanization process and enhance the physical properties of a vulcan- ized material. 3.Same as accelerating admixture.

Accent Lighting

Any directional lighting which emphasizes a particular object or draws attention to a particular area.

Acceptable Air Quality

  Inside a building, air that is free of harmful concentrations of contam- inants and that is judged acceptable to at least 80% of the building’s occupants.

Acceptance Test

 A test conducted by a pur- chaser (or an agent thereof) (a) to determine if  the material, devices, or equipment delivered conforms to the purchase contract specifications and/or (b) to determine the degree of uniformity of the product supplied by the vendor.


 A means of approach, e.g., a road, street, or walk.

Access Door

 A door, usually small, which is provided through a finished construction, as into a duct, through a ceiling, behind a wall, in a large piece of mechanical equipment, etc.; used to provide a means of inspection of equipment or services housed within.

Access Panel

A removable panel (usually secured with screws) in a frame which is usually mounted in a ceiling or wall; provides access to a concealed item that does not require frequent attention.

Access Plate

A removable plate (usually bolted in place) that provides access to an area that seldom requires attention; permits inspection of an otherwise inaccessible area.

Access Stair

A stair, from one floor level to another, which does not serve as a required exit stair. Also see exterior stair.

Access Street

A low traffic volume street,usually comprised of individual dwelling units, which conveys vehicular traffic to or from a street carrying heavier traffic.

Access Way

A roadway, usually paved, intended to provide ingress and egress of vehicular traffic from a public right of way to an off-street parking area.


1.Allowing physical contact, as by means of an easily removable cover or door or a part of the building structure or finish materials. 2.Providing access to a fixture, appliance, or piece of equipment; removal of a cover, panel, plate, or similar obstruction may be required. 3.Said of a building, facility, or site that can be approached, entered, and used by a physically disabled person.4.According to the Americans with Disabilities Act (ADA), a term used for a space that complies with the standards of the Act for  those having disabilities or impairments (including visual, hearing, mental, or mobility), and does not require the assistance of others to enter the space.

Accessible Means Of Egress

 A path of travel, usable by a mobility-impaired person, that leads to a public way.

Accessible Route

According to the ADA, a continuous, unobstructed path between all accessible elements and areas of a building, including corridors, ramps, and elevators; the route must provide adequate clearance around desks, furniture, and the like.

Accessible Space

 A space that complies with all provisions of the Americans with Disabilities Act. 

Accessory Building

 A secondary building, whose use is incidental to that of the main build-ing located on the same plot.

Accessory Use

 The use or occupancy incidental to the principal use or occupancy of a building.


A sudden, unexpected event identifiable as to time and place. Also see occurrence.


The upward slope of a hillside.


An ornamental treatment, used over an arch, a door, or a window, composed of two ogee curves meeting in the middle; often a richly decorated molding.


A decoration added to a building with the intention of enhancing its appearance.

Accordion Door

1.Any fabric faced door  which is hung from an overhead track and folds back like the bellows of an accordion. 2.A hinged door consisting of a system of panels which are hung from an overhead track. When the door is open, the faces of the panels close flat against each other; when the door is closed, the edges of adjacent panels butt against (or interlock with) each other to form a solid barrier.

Accordion Partition

A fabric faced partition which is hung from an overhead track and folds back like the bellows of an accordion.


The placement of columns or pilasters close together, in pairs.

Accrued Depreciation

1.The reduction in actual value of property over a period of time, as a result of wear and tear, obsolescence, etc. 2. The accumulated reductions in the stated value  of property over a period of time, entered on balance sheets for accounting or tax purposes.


1.In a refrigeration system, a storage chamber for low side liquid refrigerant; also called a surge drum or surge header.2.In a refrigerant circuit, a vessel whose volume is used to reduce pulsation.


Abbr. for automatic closing device.


Abbr. for “Architects Council of Europe.” acetone A highly flammable solvent which evaporates rapidly; used in lacquers, paint removers, thinners, etc.


A colorless gas, when mixed with oxygen, burns at a temperature of about 3500C; used in welding.

Acetylene Torch

A torch, used in welding and in metal cutting, which is operated by compressed acetylene gas and oxygen.