Basic Guidelines For English Spellings
Caffeine, especially when it occurs in tea.‘Eventually it was shown that the theine of tea was identical with the caffeine of coffee, and the term theine was then dropped.’
- ‘Analysis certificates are issued for each processed batch; these certificates also state the percentage of theine and residues still left.’
Mid 19th century from modern Latin Thea (former genus name of the tea plant, from Dutch thee) + -ine.
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