abaculus
nounUS /əˈbæk.jə.ləs/
Etymology From Latin abaculus, diminutive of abacus.
1
Archaic A small tile of glass, marble, or other substance, of various colors, used in making ornamental patterns in mosaic pavements; abaciscus.
Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.