I. ˌa-prə-ˈpō, ˈa-prə-ˌ adverb
Etymology: French à propos, literally, to the purpose
Date: 1668
1. : at an opportune time : seasonably
2. : by way of interjection or further comment : with regard to the present topic
II. adjective
Date: 1686
: being both relevant and opportune
apropos comments
Synonyms: see relevant
III. preposition
Date: 1879
: apropos of