oc·​to·​thorpe ˈäk-tə-ˌthȯrp How to pronounce octothorpe (audio)
variants or octothorp
: the symbol #

Did you know?

A versatile symbol with many names (among them hash mark, number sign, and pound sign), the octothorpe has become popularized in hashtags, those words or phrases prefixed by the symbol on Twitter and other social media especially to classify or categorize the accompanying text. The octothorpe is believed to have been adopted by the telecommunications industry with the advent of touch-tone dialing in the 1960s, but it remains unknown how, exactly, the symbol got its odd name. The octo- part almost certainly refers to the eight points on the symbol, but the -thorpe bit is mysterious. One story links it to a telephone company employee who happened to burp while talking about the symbol with coworkers. Another relates it to the athlete Jim Thorpe and the campaign to restore posthumously his Olympic medals, which were taken away after it was discovered that he played baseball professionally previous to the 1912 Games. A third claims it derives from an Old English word for "village."

Word History


octo- + thorp, of unknown origin; from the eight points on its circumference

First Known Use

1971, in the meaning defined above

Time Traveler
The first known use of octothorpe was in 1971


Dictionary Entries Near octothorpe

Cite this Entry

“Octothorpe.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/octothorpe. Accessed 20 Feb. 2024.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!