hashtag /ˈhæʃˌtæɡ/noun 2verb 1forms 3 noun2 •(Internet) A metadata tag, signaled by a preceding hash sign (#), used to label content.I support the hash tag convention: http://tinyurl.com/2qttlb #hashtag #factoryjoe #twitter — 2007 •(Internet, informal) The hash sign itself, especially when used as part of a hashtag.You're perpetually stoned, aren't you? Hashtag four twenty four seven. — 2018 verb1 •(Internet) To label (a message) with a hashtag. formshashtagged · hashtagging · hashtags