English

Noun

abaciscus ‎(plural abacisci or abaciscuses)^[1]

1. (archaic) One of the tiles or squares of a tessellated pavement; an abaculus. [First attested in the mid 18^th century.]^[1]

References

1. 1 2 Lesley Brown (editor), The Shorter Oxford English Dictionary, 5th edition (Oxford University Press, 2003 [1933], ISBN 978-0-19-860575-7), page 2