hashtag

American  

[hash-tag] / ˈhæʃˌtæg /

noun

1. (on social media websites)

   1. 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.

   2. a hash mark used in this way.

2. 1. a word or phrase preceded by a hash mark (#) or by the word hashtag , used to add wit or emphasis to a spoken or written statement.

   2. a hash mark or the word hashtag used in this way, as in the sentence His goodbye was so hashtag awkward.

---

verb (used with or without object)

hashtagged, hashtagging

1. to add a hashtag to (a word, topic, or message).

   Someone on Twitter just hashtagged the film festival.

hashtag British  

/ ˈhæʃˌtæɡ /

noun

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

---

Usage

What does hashtag mean? A hashtag is a word or phrase preceded by a hash mark (#), also known as a pound sign, used primarily on social media. On social media, hashtags provide users a way to search for posts related to the word or phrase in the hashtag. You can click on a hashtag to see a list of recent posts that include that keyword. (A couple of our favorites are #WordOfTheDay and #WordNerd.)To hashtag means to add a hashtag to a word, topic, or message, as in We hashtag our posts about history with #HistoryMatters so you can find them easily. Example: Use the hashtag #petthedog with a video of you petting your dog for a chance to win our contest.

Etymology

Origin of hashtag

First recorded in 2005–10; hash (mark) + tag ¹ (in the sense “a label or keyword”)

Explanation

A hashtag is a keyword or phrase that's used on social media. By searching for a certain hashtag, you can easily find the cute cat content you're looking for. To create a hashtag, type # (which is variously called the "number sign," "pound sign," or "hash") followed by a word. You might post about a successful pie-baking experiment and use the hashtags #pie, #sourcherrypie, and #baking. And if you're looking for content about capybaras, just click on #capybara and you'll see a list of every photo or post with that hashtag. The very first hashtags appeared on Twitter in 2007, and they quickly spread across all social media.

Example Sentences

Mr. Bernard, who teaches the history of science at Leuphana University in Lüneburg, Germany, has written on the history of the elevator and the theory of the hashtag.

From The Wall Street Journal • Apr. 15, 2026

Then, finally, the truth about the fact is revealed, with Wiles sharing that her neighbors were of a more high-brow Hollywood class, sharing an image of Craig and Weisz with the hashtag #holyairball.

From MarketWatch • Apr. 15, 2026

Bethany is one of a growing number of people documenting their experiences on social media, using the hashtag TSW, which stands for topical steroid withdrawal.

From BBC • Mar. 28, 2026

The overkill hits its nadir when the Bride repeatedly wails the survivors’ hashtag, “Me too!”

From Los Angeles Times • Mar. 4, 2026

BLM began with the use of the hashtag #BlackLivesMatter on social media after the acquittal of George Zimmerman in the shooting death of African American teenager Trayvon Martin.

From "1919 The Year That Changed America" by Martin W. Sandler