Definition of "octothorpe" [octothorpe]

• The symbol (#). (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The term octothorpe was coined by engineers at Bell Laboratories in the early 1960s, who wanted a name for one of two non-number function symbols on the first touch-tone keypads the other was the *, which they called a sextile."
• "The octothorpe is the essential symbol in the formation of a hashtag, a marker that allows 140-character tweets to be grouped together by subject"
• "Once again, Quinion's World Wide Words explains the history: "octothorpe" was Bell Labs jargon for one of those two function keys on touch-tone telephones that got labeled with symbols instead of numbers."