ap·ro·pos

adj.

Being at once opportune and to the point. See Synonyms at relevant.

adv.

1. At an appropriate time; opportunely.

2. By the way; incidentally: Apropos, where were you yesterday?

prep.

With regard to; concerning: Apropos our date for lunch, I can't go.

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[French à propos : à, to (from Old French a, from Latin ad-; see ad-) + propos, purpose (from Latin prpositum, neuter past participle of prpnere, to intend; see propose).]