Architectural and Engineering Glossary


Allotment Garden

Any privately or publicly owned garden area which has been divided into plots for assignment to individuals for their use.


A pattern covering an entire surface;usually one which is repeated.


On drawings,abbr.for “allowance.”

Allowable Load

The load which induces the maximum permissible unit stress at a critical section of a structural member.

Allowable Pile Load

The allowable concentrically applied load which is permitted along the central axis of a pile.

Allowable Soil Pressure

See allowable bearing value.


A composition of two or more metals fused together,usually to obtain a desired property.

Alloy Steel

Steel containing one or more alloying elements other than carbon,such as chromium,molybdenum,or nickel,which have been added (in an amount exceeding a specified minimum) to impart particular physical,mechanical,or chemical properties.


See alure.

Alluvial Deposit

Earth,sand,gravel,or other rock or mineral materials transported and laid down by flowing water.


Gravel,sand,silt,soil,or other material that is deposited by running water.


On drawings,abbr.for “alarm.”


See ambry.


In Arabian architecture,a niche in a mosque which marks the direction of Mecca.


See ambry.


An aureole of elliptical form.


A building or part thereof where alms are distributed.


Same as almariol.


In Hispanic architecture,brickwork intermixed with azulejos;used as flooring.


1.A building in which charity was distributed to the poor;found in England and in some early American settlements and cities;also see poorhouse.2.An almonry.

Alpha Brass

An alloy containing 51 to 61% copper and 39 to 45% zinc;used in hot-water systems because of its corrosion resistant properties.

Alpha Gypsum

A specially processed gypsum having low consistency and high compressive strength,often exceeding 5,000 lb per sq in. (352 kg per sq cm).


On drawings,abbr.for “alternate.”


A light ornamental structure on a roof that serves much the same function as a gazebo. 


1.An elevated table,slab,or structure,often of stone,rectangular or round,for religious rites,sacrifices,or offerings.2.The Communion table in certain churches.

Altar Frontal

An ornamental hanging or panel for the front of an altar.

Altar Of Repose

In a Roman Catholic church,a side altar,repository,or storage niche where the Host is kept from Maundy Thursday to Good Friday.

Altar Rail

A low rail or barrier in front of the altar,running transversely to the main axis of the church and separating the officiating clergy from the other worshipers.

Altar Screen

A richly decorated partition of stone,wood,or metal,separating the altar from the space behind it.

Altar Slab,altar Stone

A flat stone or slab forming the top of an altar.

Altar Tomb

A raised tomb,or monument covering a tomb,whose shape resembles an altar.


A decorative screen,painting,or sculpture above the back of an altar.


Construction in a building which may change the structural parts,mechanical equipment,or location of openings,but does not increase the overall area of dimensions of the building.


1.A construction project (or portion of a project) comprising revisions within or to prescribed elements of an existing structure,as distinct from additions to an existing structure.2.Remodeling.


A change in work,1described in the contract documents for a building that gives the owner the option of selecting various products,materials,or systems,and/or the right to add or delete portions of the work.

Alternate Bid

The amount stated in the bid to be added to or deducted from the amount of the base bid if the corresponding change in project scope or alternate materials and/or methods of construction is accepted.


A generator of alternating current which is produced by the turning of its rotor.


On drawings,abbr.for aluminum.


The oxide of aluminum;an important constituent of the clays used in brick,tile,and refractories.


British term for aluminum.

Aluminous Cement

See calcium aluminate cement.

Aluminum Brass

Brass to which aluminum has been added to increase its corrosion resistance.

Aluminum Bronze

A copper-aluminum alloy,usually with 3 to 11% aluminum;may contain additional additives;has good corrosion resistance and may be cast or coldworked.

Aluminum Door

A door having aluminum stiles and rails;usually glazed.

Aluminum Foil

Very thin aluminum sheet (less than 0.006 in.or 0.15 mm);usually used for thermal insulation and vapor barriers.

Aluminum Oxide

Same as alumina.

Aluminum Paint

A paint made with aluminum paste and a film forming vehicle (such as a varnish);a good heat and light reflector;has good water impermeability.

Aluminum Powder

Small flakes of aluminum metal obtained by stamping or ballmilling foil in the presence of a fatty lubricant,such as stearic acid,which causes the flakes to orient in a pattern to give high brilliance.Usually supplied in paste form wetted with mineral spirits.

Aluminum Primer

An aluminum-based primer,1 that has excellent water resistant properties.

Aluminum Silicon Bronze

An alloy consisting chiefly of copper with aluminum and silicon added to give it greater strength and hardness.