Disinterested and Uninterested
Contrary to popular usage, these words aren’t synonymous. A “disinterested” person is someone who’s impartial. For example, a hedge fund manager might take interest in a headline regarding stock performance with which he has no money invested. He’s “disinterested,” i.e., he doesn’t seek to gain financially from the transaction he’s witnessed. Judges and referees are supposed to be “disinterested.” If the sentence you’re using implies someone who couldn’t care less, chances are you’ll want to use “uninterested.”