emeritus

The adjective emeritus is unusual in two ways: it's frequently used postpositively (that is, after the noun it modifies), and it has a plural form—emeriti—when it modifies a plural noun in its second sense. If you've surmised from these qualities that the word is Latin in origin, you are correct. Emeritus, which is the Latin past participle of the verb emereri, meaning "to serve out one's term," was originally used to describe soldiers who had completed their duty. (Emereri is from the prefix e-, meaning "out," and merēre, meaning "to earn, deserve, or serve"—also the source of our English word merit.) By the early 18th century, English speakers were using emeritus as an adjective to refer to professors who had retired from office. The word eventually came to be applied to other professions where a retired member may continue to hold a title in an honorary capacity.