apropos (adv.) Look up apropos at Dictionary.com
1660s, "opportunely," from French à propos "to the purpose," from propos "thing said in conversation, talk; purpose, plan," from Latin propositium "purpose," past participle of proponere "to set forth, propose" (see propound). Meaning "as regards, with reference to" (with of) is 1761, from French. As an adjective, "to the point or purpose," from 1690s.