Abaculus
Pronunciation : A*bac"u*lus
Part of Speech : n.; pl. Abaculi.
Etymology : [L., dim. of abacus.] (Arch.)
Definition : Defn: A small tile of glass, marble, or other substance, of various colors, used in making ornamental patterns in mosaic pavements. Fairholt.
Source : Webster's Unabridged Dictionary, 1913