Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A searchable keyword or sequence of characters prefixed with the pound sign (#), included in a tweet or other electronic communication and indicating the subject matter.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun Internet A tag embedded in a message posted on the Twitter microblogging service, consisting of a word within the message prefixed with a hash sign (#).
  • verb transitive, Internet To label (a message) with a hashtag.

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[hash + tag.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From hash +‎ tag.

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Examples

Comments

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  • #

    "Hashtags are a pretty simple concept that really enhance the Twitter experience. They enable easy categorization of tweets for effective future searching. That means that if for example, you are tweeting about the iPhone, you simply insert a # before the word iPhone. Anyone who then searches hashtags.org or Twitter search, for the #iPhone term, will come up with your tweet as well as all tweets on the subject." --hizfuld, "Ten Things you Must Know before Using Twitter"

    April 14, 2009

  • Or hashtag could be that special day when you just make a complete hames of everything you put your hand to.

    April 14, 2009

  • WORD: hashtag

    DEFINITION: Another name for the octothorpe. See also the Wikipedia page for hashtag:

    << http://en.wikipedia.org/wiki/Hashtag >>

    EXAMPLE: ' From the Times Literary Supplement, Sept. 30:

    ' Twitter users may not know it but they are likely to be addicts of the octothorpe , a symbol with a Latin provenance. Now more commonly known as the hashtag, the octothorpe first served as an abbreviation of "libra pondo" ("a pound by weight") in medieval England. The "lb" was written with a tilde just above the mid-height of the letters to signify a contraction, and was thence corrupted into "#" by rushing scribes. "Pound" later became "number" before evolving into a variety of different signifiers, including a copy-editor's space, a chess player's checkmate and a Tweeter's keyword. How it came to be known as the octothorpe is quite another matter. '

    --- Reprinted in the Wall Street Journal. "Notable & Quotable." October 28, 2013. (Page A15).

    November 1, 2013