late 14c., twiteren, in reference to birds, of imitative origin (compare Old High German zwizziron, German zwitschern, Danish kvidre, Old Swedish kvitra). The noun meaning "condition of tremulous excitement" is attested from 1670s. The microblogging service with the 140-character limit was introduced in 2006. The following is considered an unrelated word of obscure origin:
TWITTER. 1. "That part of a thread that is spun too small." Yarn is said to be twined to twitters, when twined too small, S. Hence, to twitter yarn, to spin it unequally, A. Bor. Ray.
2. It is transferred to any person or thing that is slender or feeble. It is said of a lank delicate girl: "She is a mere twitter," S. [Jamieson, "Etymological Dictionary of the Scottish Language," Edinburgh, 1808]