apropos

Từ điển American Heritage Dictionary 4th

ap·ro·pos (ăp'rə-pōʹ)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. [French à propos: à, to (from Old French a, from Latin ad-. See ad-) + propos, purpose (from Latin prōpositum, neuter past participle of prōpōnere, to intend. See propose).]

• Từ đồng nghĩa / Synonyms:
  by the way, by the bye, incidentally, seasonably, timely, well-timed