/let"is/ , n.
1. a cultivated plant, Lactuca sativa, occurring in many varieties and having succulent leaves used for salads.
2. any species of Lactuca.
3. Slang. U.S. dollar bills; greenbacks.
[ 1250-1300; 1925-30 for def. 3; ME letuse, appar. laitues, pl. of laitue lactuca a lettuce, perh. deriv. of lac, s. lact- milk, with termination as in eruca ROCKET 2 (or by assoc. with Gk galaktoûchos having milk) ]