Disinterested - uninterested
Disinterested and uninterested are commonly confused. They have different meanings that are both useful. University teachers care - quite rightly - that their students should not confuse them.
The confusion arises because these words are negatives of two different meanings of interest. Interest means:
- first, 'the advantage or benefit one may gain from, or influence in, something'. (In its restricted sense, this refers to 'financial interest', most restrictedly the money paid by a borrower to a lender.) The opposite of this is disinterested, which means 'having nothing to gain or lose from' (for example, a decision). If you watch a sports match between two teams that you do not support, you are a 'disinterested spectator'. You may be very interested, in the second sense.
- second, 'the level of involvement (or mental activity) stimulated by something'. For example, I am very interested in Shakespeare; Selene's research interests me; etc. The opposite of this is uninterested. (If you are extremely uninterested, it might be boring.)
Do not confuse these words. Think that if you are on trial for a serious offence, you should hope for a judge who is disinterested; but not for one who is uninterested. The former will not take sides on the grounds that s/he does not stand to profit; the latter may well be so bored that s/he takes no notice.