The word is typically used as a postpositional adjective but can also be used as a preposition adjective. It is frequently capitalized when it forms part of a title. The word originated in the mid-18th century from Latin as the past participle of emereri meaning to "earn one's discharge by service". Emereri itself is a compound of the prefix e- (a variant of ex-) meaning "out of or from" and merēre meaning "earn".
Emeritus does not imply that the person must be retired from all duties of his or her previous title, nor does it imply that the person is engaged in the duties of his or her previous title.