? Abbr. for angstrom.

A 1.Abbr. for ampere, a unit of electric current. 2.Abbr. for area.

AA Abbr. for the “Architectural Association,” the largest school of architecture in England; address 34–36 Bedford Square, London, WC1B 3ES.

AAA Abbr. for “Architectural Aluminum Association.”

AAI Abbr. for “Architectural Association of Ireland.”

AAMA Abbr. for “Architectural Aluminum Manufacturers Association.”

A&E See architect-engineer.

Aaron’s rod An ornament or molding consisting of a straight rod from which pointed leaves or scroll work emerge on either side, at regular intervals.

abaciscus 1.A tessera, as used in mosaic work. Also called abaculus. 2.A small abacus.

abacus The uppermost member of the capital of a column; often a plain square slab, but sometimes molded or otherwise enriched.

abamurus A buttress, or a second wall added to strengthen another.

abate 1. To remove material, as in stone carving. 2. In metalwork, to cut away or beat down so as to show a pattern or figure in low relief.

abated Said of a surface that has been cut away or beaten down so as to show a pattern or figure in low relief; also see relief.

abatement The wastage of wood when lumber is sawed or planed to size.

abat-jour 1. In a wall, an aperture whose sides have been cut back and/or whose underside has been sloped downward so as to admit a greater amount of light to the interior of the room. 2. A skylight.

abaton A sanctuary not to be entered by the public; a holy of holies.

abat-sons Descriptive of a surface said to reflect sound downward.

abat-vent 1. Louvers that are placed in an exterior wall opening to permit light and air to enter, but break the wind. 2.A sloping roof. 3. In the French Vernacular architecture of New Orleans, an extension of a roof over a sidewalk.