Chem. Also † thei·na. [f. mod.L. thea TEA + -INE5.] A vegetable alkaloid, originally thought to be a principle peculiar to tea, but found to be identical with CAFFEINE.
1838. T. Thomson, Chem. Org. Bodies, 295. Oudry has … announced that he has discovered in ten a salifiable basis, to which he has given the name of theina.
1842. Penny Cycl., XXIV. 304/2. Thein, or Theina, the peculiar principle of tea.
1853. Ure, Dict. Arts, II. 834. Theine was obtained from coffee by the same process slightly altered.
1863–72. Watts, Dict. Chem., I. 707. Oudry…, in 1827, found in tea a crystalline substance, which he called theine.
1881. A. Griffith, in Science Gossip, No. 203. 248. Tea contains from a half to five per cent. of theine.
