Meaning

noun a professor or minister who is retired from assigned duties

adjective honorably retired from assigned duties and retaining your title along with the additional title `emeritus' as in `professor emeritus'

originThe adjective is a learned borrowing from Latin ēmeritus (“(having been) earned, (having been) merited; (having been) served, having done one’s service”), the perfect passive participle of ēmereō (“to earn, merit; to gain by service; (military) to complete one’s obligation to serve, to serve out one’s time”), from ex- (prefix meaning ‘away; out’) + mereō (“to deserve, merit; to acquire, earn,…

Etymology from Wiktionary, CC BY-SA 3.0