HASHTAG

Etymology

Noun

hashtag (plural hashtags)

(Internet) A metadata tag, signaled by a preceding hash sign (#), used to label content. [from 2007]

(internet, informal) The hash sign itself.

Verb

hashtag (third-person singular simple present hashtags, present participle hashtagging, simple past and past participle hashtagged)

(transitive, Internet) To label (a message) with a hashtag.

Source: Wiktionary