/ ˈletɪs; NAmE / noun
[ U , C ] a plant with large green leaves that are eaten raw, especially in salad. There are many types of lettuce :
a bacon, lettuce and tomato sandwich
Buy a lettuce and some tomatoes.
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WORD ORIGIN
Middle English : from Old French letues , laitues , plural of laitue , from Latin lactuca , from lac , lact- milk (because of its milky juice).