[Fr. from L. lactuca, which is from lac, milk, the plant having a milky juice.] An annual plant, supposed to be a native of the East Indies ; cultivated from remote antiquity, and now grown all over the world where the climate admits of it. The two principal kinds are the coss lettuce, with oblong upright leaves, and the cabbage lettuce, with rounded leaves and a head like a cabbage ; and of these two kinds there are many varieties. The leaves of lettuce are used as a salad, and though they do not contain much nourishment, they are easily digested and gently laxative. Lettuce-opium is made from the juice of the plant, and is used medicinally to allay pain and induce sleep.