hashtag

[ hash-tag ]
/ ˈhæʃˌtæg /
Digital Technology

noun

(on social media websites) a word or phrase preceded by a hash mark (#), used within a message to identify a keyword or topic of interest and facilitate a search for it: The hashtag #sandiegofire was used to help coordinate an emergency response to the fire.
a hash mark used in this way.

verb (used with or without object), hash·tagged, hash·tag·ging.

to add a hashtag to (a word, topic, or message): Someone on Twitter just hashtagged the film festival.

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Origin of hashtag

2005–10; hash (mark) + tag1 (in the sense “a label or keyword”)

Example sentences from the Web for hashtag

British Dictionary definitions for hashtag

hashtag
/ (ˈhæʃˌtæɡ) /

noun

(on the Twitter website) a word or phrase preceded by a hash mark, used to denote the topic of a post