n. (pl. -oes)
1 a any of 28 small oblong pieces marked with 0-6 pips in each half. b (in pl., usu. treated as sing.) a game played with these.
2 a loose cloak with a mask for the upper part of the face, worn at masquerades.
Phrases and idioms:
domino theory the theory that a political event etc. in one country will cause similar events in neighbouring countries, like a row of falling dominoes.
Etymology: F, prob. f. L dominus lord, but unexplained

Useful english dictionary. 2012.