abaciscus

Noun
(plural abacisci or abaciscuses)
- (archaic) One of the tiles or squares of a tessellated pavement; an abaculus. [First attested in the mid 18th century.]
Origin
From New Latin, from Ancient Greek ἀβακίσκος (abakiskos, “a coloured stone for laying mosaic”), diminutive of ἄβαξ (abaks, “board”). See abacus.