n. An insulting or suggestive Twitter post that indirectly mentions another Twitter user, thus reducing the chance that the other person will see the message.
2014
Much ink and many, many snide subtweets have been spilled over the question of whether Obamacare’s expansion of health insurance will actually generate health gains.
2014
The four ex-chiefs of staff—Nick Kouvalis, Amir Remtulla, Earl Provost, and Mark Towhey—were all key architects of Ford’s early success as mayor. All of them now have other jobs, and Towhey spends his days mocking his former boss with witty subtweets.
2009 (earliest)
When you retweet (RT) something but alter it in a subversive way it needs to be called a subtweet (ST).
On Twitter, if you include another user's account name, preceded by @, that person automatically sees your message (this is called a mention). A subtweet leaves out the "@" (or uses the person's real name, if it's different from their account name), so the other user doesn't automatically see the message.