Domino

n. pl. Dominos or (esp. the pieces for a game) Dominoes (#).

1. A kind of hood worn by the canons of a cathedral church; a sort of amice.
2. A mourning veil formerly worn by women.
3. A kind of mask; particularly, a half mask worn at masquerades, to conceal the upper part of the face. Dominos were formerly worn by ladies in traveling.
4. A costume worn as a disguise at masquerades, consisting of a robe with a hood adjustable at pleasure.
5. A person wearing a domino.
6. One of the pieces with which the game of dominoes is played.
fall like dominoes .
To fall sequentially, as when one object in a line, by falling against the next object, causes it in turn to fall, and that second object causes a third to fall, etc.; the process can be repeated an indefinite number of times.