abat-voix In a church, a sound reflector behind and over a pulpit.

abbey A monastery or convent; particularly the church thereof.

abbreuvoir Same as abreuvoir.

ABC 1. Abbr. for “aggregate base course.” 2. Abbr. for “Associated Builders and Contractors.”

A-block A hollow, concrete masonry unit with one end closed and the opposite end open, having a web between, so that two cells are formed when the block is laid in a wall.

Abney level A hand level used for measuring vertical angles; comprised of a small telescope, bubble tube, and graduated vertical arc.

above-grade building volume The volume of a building (in cubic feet or in cubic meters) measured from the average adjoining grade level to the average roof level, and from outside to outside of exterior walls, but not including breezeways, porches, or terraces.

abrade To wear away or scrape off a surface, especially by friction.

Abrams’ law A statement applying to given concrete materials and conditions of test: For a mixture of workable consistency, the strength of concrete provided by the mixture is determined by the ratio of the amount of water to the amount of cement.

abrasion A surface discontinuity caused by roughening or scratching.

abrasion resistance The ability of a surface to resist being worn away or to maintain its original appearance when rubbed with another object.

abrasion resistance index A measure of the abrasion resistance of a vulcanized material or synthetic rubber compound relative to that of a standard rubber compound under specified conditions.

abrasive A hard substance for removing material by grinding, lapping, honing, and polishing. Common abrasives include silicon carbide, boron carbide, diamond, emery, garnet, quartz, tripoli, pumice, diatomite, metal shot, grit, and various sands; usually adhered to paper or cloth.

abraum A red ocher used to stain mahogany.

abreuvoir In masonry, a joint or interstice between stones, to be filled with mortar or cement.

ABS Abbr. for acrylonitrile-butadiene-styrene.

abscissa In the plane Cartesian coordinate system, the horizontal coordinate of a point on a plane; the x-coordinate, obtained by measuring the distance from the point to the y-axis along a line parallel to the x-axis.