adj. & adv.
adj. 1 to the point or purpose; appropriate (his comment was apropos). 2 colloq. (often foll. by of) in respect of; concerning (apropos the meeting; apropos of the talk).
adv. 1 appropriately (spoke apropos). 2 (absol.) by the way; incidentally ( apropos, she's not going).
[ F à propos f. à to + propos PURPOSE ]