Someone who is so indescribably unattractive that it is impossible to fuck them.
"I've thought about it dude, but she isn't just ugly, she's mean. Totally uneffable."
by Matty B Good May 19, 2009
1 more definition
short for un-effing-believable; un-fucking-believable; unbelievable
"That concert was uneffable!" -Roger
by MissJuly October 15, 2013