tweeter

noun

1. An electronic speaker designed to produce high-frequency sound.
2. One who or that which makes a tweeting noise.

   “The little tweeter birds that had kept her company this morning were now absent, leaving nothing but the whisper of the trees as a light breeze gently wandered by.”

3. One who posts messages ("tweets") on the social networking site Twitter.

   “The latest addition to these daily outpourings are suggested tweets to circulate. Fortunately I am not a tweeter, so I swiftly delete all these unread.”

4. (broadly)A poster on a microblogging social networking service.