domino

Concise Oxford English Dictionary © 2008 Oxford University Press:
domino /ˈdɒmɪnəʊ/

▶noun (pl. dominoes)

• 1 any of 28 small oblong pieces marked with 0–6 pips in each half.

  ■ (dominoes) [treated as sing.] the game played with dominoes, each player in turn trying to lay down a domino with a value matching that of a piece at either end of the line already formed.

• 2 historical a loose cloak, worn with a mask for the upper part of the face at masquerades.

– origin C17: from Fr., denoting a hood worn by priests in winter, prob. based on L. dominus ‘lord, master’.