Tweet is a short message posted on the social media platform Twitter (now called X). The word comes from the chirping sound birds make, and like a bird's quick song, a tweet is meant to be brief: the platform originally limited posts to just 140 characters, though that limit has since expanded.

When someone tweets, they share a thought, news update, joke, or observation with anyone who follows their account. A tweet might announce breaking news, share a funny observation about daily life, or comment on current events. Politicians tweet to communicate directly with voters. Scientists tweet about their research. Your favorite author might tweet about the book they're writing.

People can retweet messages they find interesting, spreading them to their own followers. You might see someone say “that tweet went viral,” meaning it got shared so many times that millions of people saw it.

The word has become common enough that people use it even when they're not talking about the platform itself. Someone might say “I should tweet that,” meaning “that's worth sharing” or “that's so funny it deserves a wider audience,” whether or not they actually post it online.