a word or phrase preceded by a hash sign (#), used on social media sites and applications, especially Twitter, to identify digital content on a specific topic

spammers often broadcast tweets with popular hashtags even if the tweet has nothing to do with them

the hashtag #riotcleanup is being used by community members to coordinate some street cleaning

add a hashtag to (digital content) to identify it as concerning a specific topic

the athlete hashtagged his post #luckyman