OTP means "One True Pairing." It is a term in Fanfiction and is used in fandom. It is a person's favorite and "true" pairing of two characters. OTP is mainly known in the anime Fanfiction world.
IchiRuki is so my OTP!
by LilyM99 June 23, 2014
OTP is an abbreviation for 'On The Phone.'
by turtle-shell September 26, 2007
OTP means On The Prowl!!! as in "feeling frisky" like a cat who is out on the hunt to get her prey! It can be used in a sexy way (like "she is looking to get some tonight"), or in a joking way about being overly desperate about being on the hunt for anyone.
When she saw her friend(who was wearing a short, tight red dress and high heels, looking very sexy), she exclaimed, "Oooh! I see you are OTP tonight!"
by CarolinaAAAH! January 29, 2008