Abaculus

A*bac"u*lus (&adot;b*&abreve;k"&usl;*l&ubreve;s), n.; pl. Abaculi (-l&imacr;). [L., dim. of abacus.] (Arch.) A small tile of glass, marble, or other substance, of various colors, used in making ornamental patterns in mosaic pavements. Fairholt.