Merriam-Webster's Collegiate® Dictionary, 11th Edition
LOO
I. noun
Etymology: short for obsolete English lanterloo, from French lanturelu twaddle
Date: 1675
an old card game in which the winner of each trick or a majority of tricks takes a portion of the pool while losing players are obligated to contribute to the next pool, money staked at loo,
II. transitive verb
Date: 1680
to obligate to contribute to a new pool at loo for failing to win a trick,
III. noun
Etymology: origin unknown
Date: 1940
toilet 3