Usage Note: The word uninterested, which properly means “taking no interest, not interested,” is sometimes used to mean “not favoring either side, unprejudiced,” where one would expect to see disinterested instead. The Usage Panel roundly disapproved of this usage in our 2001 survey, with 96 percent rejecting the sentence Every historian ought to be extremely uninterested; he ought neither to praise nor to blame those he speaks of. See Usage Note at disinterested.
(comparative more uninterested, superlative most uninterested)
From un- + interested.