Old English togædere "so as to be present in one place, in a group, in an accumulated mass," from to (see to) + gædere "together" (adv.), apparently a variant of the adverb geador "together," from Proto-Germanic *gaduri- "in a body," from PIE *ghedh- "to unite, join, fit" (see good, and compare gather).
In reference to single things, "so as to be unified or integrated," from c. 1300. Adjective meaning "self-assured, free of emotional difficulties" is first recorded 1966. German cognate zusammen has as second element the Old High German verbal cognate of English same (Old English also had tosamne "together").
updated on February 11, 2014