dominoyoudaoicibaDictYouDict[domino 词源字典]
domino: [18] The word domino was borrowed from French, where it originally signified (in the 16th century) a sort of hooded cloak worn by priests. It presumably represents a form of Latin dominus ‘lord, master’, but the reason for the application has never been satisfactorily explained (one suggestion is that it comes from the ritual formula benedicamus Domino ‘let us bless the Lord’).

By the time English acquired it, it had come to mean ‘hooded cloak with a halfmask, worn at masquerades’, and by the 19th century it was being used for the mask itself. It is far from clear whether the application to the game played with small rectangular blocks, which dates in English from the 19th century, represents a new use of the same word or a return to the original Latin, but either way the reason behind the usage is not known.

A possibility that has been advanced is that the winner of the game originally shouted domino! ‘lord!’.
[domino etymology, domino origin, 英语词源]
domino (n.)youdaoicibaDictYouDict
1801, from French domino (1771), perhaps (on comparison of the black tiles of the game) from the meaning "hood with a cloak worn by canons or priests" (1690s), from Latin dominus "lord, master" (see domain), but the connection is not clear. Klein thinks it might be directly from dominus, "because he who has first disposed his pieces becomes 'the master.' " Metaphoric use in geopolitics is from April 1954, first used by U.S. President Eisenhower in a "New York Times" piece, in reference to what happens when you set up a row of dominos and knock the first one down.