The Collaborative International Dictionary of English v.0.48:

Loo \Loo\ (l[=oo]), v. t. [imp. & p. p. Looed (l[=oo]d); p.
   pr. & vb. n. Looing.]
   To beat in the game of loo by winning every trick. [Written
   also lu.] --Goldsmith.
   [1913 Webster]