Little People of America is demanding an apology from Bill Walton after he said the m-word twice on air on Thursday night ... calling his use of the term both "deplorable and inexcusable."
The org. -- regarded as the largest dwarfism support group in the world -- blasted the college basketball commentator in a statement to TMZ Sports on Friday ... less than 24 hours after Walton said the derogatory term while broadcasting the USC vs. Arizona State game.
Walton said at halftime while trying to praise the arena's in-game host, "He does not need a little chair because he is a giant in a world full of shriveling m*****s."
He used the word again when turning his attention toward his broadcast partner, Dave Pasch -- who awkwardly laughed off the whole situation.
The org. says Walton should have known better -- saying "ignorance at this point is simply not an excuse" -- and now, they want him to say he's sorry.
"Those who use the term m***** or any terminology that further stigmatizes people born with dwarfism are asked to educate themselves to eradicate this word," LPA officials said.
"Little People of America is asking Bill Walton to issue an apology and vow to use appropriate terminology rooted in respect and dignity going forward."
LPA also took aim at Pasch -- saying he should have denounced Walton's use of the term live on air.
"We hope that in the future Dave Pasch will speak up against disparaging language in solidarity with our organization fighting for disability equity and justice."
Neither Pasch nor Walton has publicly commented on the matter.