look up any word, like fellated:
 
15.
A device used by fat girls to prevent their hot friends from going home with you.
John was about to go home with some hot blonde until her fat friend cockblocked him and went home with her instead to eat candy bars and watch the Tyra Banks show
by TheFrost February 23, 2007
 
16.
A special door that keeps male chickens from entering a henhouse.
"Dude, that rooster is trying to get at the hens, but the cockblock is keeping him out!"
by Oleg Yavorsky March 22, 2009
 
17.
1. Someone who stops someone from having any type of relationship with someone else due to reasons of jealousy or anger.

2. Someone or something who stops sex from occuring with thier presence, accident or not.
1a. A girl who is ugly and/or fat who has a pretty friend. She stops guys from dating this pretty girl because she thinks 'if I can't, than niether can you'. What a bitch.

1b. A girl who is ugly and fat who got rejected by a man. She then spreads rumours and lies to anyone the man has his eye on trying to get them to reject him. WHAT A BITCH

2. A kid wants to score but his parents are always around, never leaving an opportunity. They are cock blocking.
by Cybernetico January 01, 2005
 
18.
to interfere with a man trying to pick up a girl.
((Mike is Hitting on a Girl as Bobby Yells Across The Room))
Bobby : "Hey Mike did you get your herpes medicine yet?"
Mike : "Man, why you always tryna cock block me?!"
by xxcHoLa May 24, 2006
 
19.
interupting on a buddy or someone while he is trying to get with a girl
Wow, that guy is being a real cock-block.
by Fava October 03, 2005
 
20.
one who prevents the cock from being unleashed upon a woman.
I had a hot girl in the room, but Alex would not quit playing WoW and subsequently became a cock block.

Me: "Alex...girl...in...room.."
Alex: "no, one more raid, there's a hot sorceress in here, i think she wants to get into my pixel pants."
by DeerPark1515 November 30, 2006
 
21.
to keep a brother from getting laid with your pressence
johns little brother cock blocked him by not leaving the room.
by M&M October 23, 2003