al·ien·ist 
(ālyə-nĭst, ālē-ə-)
(ālyə-nĭst, ālē-ə-)n.
A physician who evaluates the competence of defendants to stand trial.
[Obsolete French aliéniste, psychiatrist : obsolete French aliéné, mentally ill (from past participle of aliéner, to estrange, make hostile, deprive of reason, from Old French, from Latin aliēnāre, to deprive of reason; see ALIENATE) + French -iste, -ist (from Old French; see -IST).]