Uninterest means a lack of interest, concern, or attention; disinterest means a lack of bias or prejudice: His poor vocabulary shows clear uninterest in reading, A good jury must always exhibit disinterest in a trial. The past-tense adjective disinterested takes a more nuanced meaning than its root form—it indicates not only a lack of bias but also a lack of personal gain. The past-tense adjective uninterested retains the same meaning of its root form. Both past-tense adjectives appear more frequently in modern usage than their noun equivalents.