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Used to express love. Derives from the symbol for heart, <3 , which was typed incorrectly as <#, and then shortened into just #.

I # Arlene, she makes my world go 'round.

I feel so much # for Arlene right now.
by thekeenone May 10, 2007
Used as a tagging marker in Twitter for creating lists and groups.
#wsd get immodium, lunch w/ @scobleizer
by Mlx March 01, 2008
A grid for the playing of the game Tic Tac Toe.
Hey Poindexter, take your finger out of your ass, and lets play some #!
by Malcolm X-crement December 03, 2003
The official symbol of attention seekers on the internet
Attention Whore: "#YOLO, #SWAGG, #Kony2012
by yooooollllooo February 23, 2013
a number sign. mostly used in the internet and when texting. Instead of typing the word "number", you can use this as an alternative.
zzz:what's ur #?
yyy:it's none of ur business!!
by Snaked Eyes J. Slither August 19, 2005
Used to be the sign for a number, but thanks to goddamn twitter its called a hashtag. possibly the most annoying key out there that kids use these days before the dumbest sayings and words. And don't think I'm an old party pooper because I'm 15 and saying this.
Allie: #swag
Jack: #ihateniggasstealingmybitch
Jeff: #throwbackthursday
Me: #ifuckinghatehashtags #fuckallofyou #imleaving
by ak15 November 11, 2013
the waffle key. many people use it as an abbreviation for 'number.' it looks like a waffle.(:
by justanotherloooser.(: January 02, 2010
For tweets, instagram, facebook, and such
#josh hutcherson is cuuuuuute
by first_jumper♡♥ November 24, 2013