Definition:Dominoes/Linguistic Note

Linguistic Note on Domino
The singular of dominoes is domino.

Note that in the field of recreational mathematics, the term domino may in fact be used just for the $2$-by-$1$ oblong shape, in its context of being two squares joined together by an edge.

An older meaning of the word domino is a carnival costume featuring a black robe and a mask, often white, that covers the eyes.

It is supposed that the name of the game dominoes may have derived from the carnival costume meaning.