a counting device that consists of a frame holding rods on which a specific number of beads are free to move. Each rod designates a given denomination, such as units, tens, hundreds, etc, in the decimal system, and each bead represents a digit or a specific number of digits
(architect) the flat upper part of the capital of a column
C16: from Latin, from Greek abax board covered with sand for tracing calculations, from Hebrew ābhāq dust
late 14c., "sand table for drawing, calculating, etc.," from L. abacus, from Gk. abax (gen. abakos) "counting table," from Heb. abaq "dust," from root a-b-q "to fly off." Originally a drawing board covered with dust or sand that could be written on to do mathematical equations. Specific reference to a counting frame is 17c. or later.