each of the small rectangular pieces that makes up a set, with each piece having a line drawn down the middle and a number from 0 to 6 on each half, used to play a variety of games;
e.g. He noticed that one domino had been left out when they were packing up the game box.
(noun)
(historical) a loose-fitting cloak, usually long and having a hood, worn with a mask covering the upper half of the face, at a masquerade, or the mask worn in such a setting;
e.g. Each person wore a black silk domino with their costume.