disinterested

Concise Oxford English Dictionary © 2008 Oxford University Press:
disinterested/dɪsˈɪntrəstɪd/

▶adjective

• 1 not influenced by considerations of personal advantage; impartial.

• 2 having or feeling no interest or concern.

– derivatives
disinterestedly adverb,
disinterestedness noun.

– origin C17: past part. of the rare verb disinterest ‘rid of interest’.

usage: According to traditional guidelines, disinterested should only be used to mean ‘impartial’ and should not be used to mean ‘not interested’ (i.e. as a synonym for uninterested). In fact, the earliest recorded sense of disinterested is for the disputed sense and it is in widespread use today, although it should be avoided in careful writing.