# Definition:Dominoes

## Definition

Dominoes are a set of (usually) wooden tiles:

in the shape of an oblong $2$ units by $1$ unit (of the order of an inch)
with two numbers, usually in the form of dots, usually between $0$ and $6$, one at each end, divided by a line between them, on one side only
such that each of the numbers appears paired with every number (including itself) exactly once
such that the opposite sides of the dominoes are unmarked so as to make them indistinguishable when upside down (although of course they may have a pretty design on them).

Their usual purpose is as the basis of various games, but feature significantly in the realm of recreational mathematics.

### Pips

The dots on the faces of a set of dominoes are usually referred to as pips.

## Also see

• Results about dominoes can be found here.

## Linguistic Note

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.