Legendary college football coach Gary Patterson is apologizing for using the n-word ... saying Tuesday his use of the slur was "unacceptable."
TCU's head coach didn't elaborate on when and why he muttered the word ... only adding, "I have always encouraged our players to do better and be better and I must live by the same standards."
Gary was accused on Monday of saying the word during a dispute with a Horned Frogs linebacker at a team workout this past Sunday.
In the accusation, redshirt freshman Dylan Jordan claims he was quarreling with Patterson during practice, when the coach told him, "You're a f**king brat I'll send you back to pitt," referring to DJ's hometown of Pittsburgh, Kansas.