Definition of "tweet" []

• A weak chirping sound, as of a young or small bird. (noun)
• To utter a weak chirping sound. (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Mr. Lincoln, imitating the bird, said: '_Tweet, tweet, tweet_; isn't he singing sweetly?'"
• "As I caught sight of him, he was straightening himself up, with a pretty, self-conscious air, at the same time spreading his white-edged tail, and calling, _Tweet, tweet, tweet_. ["
• "Even one successful hacked tweet from the account of a trusted user can have serious repercussions, especially if the bogus tweet is “retweeted” by followers to still more people."