"in addition, in excess," late Old English, stressed variant of Old English preposition to "in the direction of, furthermore" (see to). The spelling with -oo is from late 16c. Use after a verb, for emphasis (as in did, too!) is attested from 1914. German zu unites the senses of English to and too. Slang too-too "excessive in social elegance" first recorded 1881. Too much is from 1530s as "more than can be endured;" sense of "excellent" first recorded 1937 in jazz slang.