1940s: many theories have been put forward about the word's origin: one suggests the source is Waterloo, a trade name for iron cisterns in the early part of the century; the evidence remains inconclusive
loo2 noun
[mass noun]a gambling card game, popular from the 17th to the 19th centuries, in which a player who fails to win a trick must pay a sum to a pool 卢牌戏(17至19世纪盛行的设有赌金、罚金的纸牌赌博游戏)
语源
late 17th cent.: abbreviation of obsolete lanterloo from French lanturlu, a meaningless song refrain