APROPOS (or A PROPOS): [preposition] “with reference to; concerning: she remarked apropos the initative, ‘It’s not going to stop the abuse.’” —New Oxford American Dictionary
Apropos does not mean “appropriate.” That really should settle the issue, but the denseness of corporate culture and my own verbosity means I’ll go on for a few more paragraphs.
Despite their seeming similarity, apropos and appropriate do not share an etymology. Apropos derives from the French à propos (“to the purpose of”), whereas appropriate comes from the Latin for “to make one’s own” (hence the verb appropriate). Traditionally, apropos occupied the same niche as in re, as to, regarding or the pedestrian about — useful for pomping up your speech, as in “Feedback apropos the budget should be directed to the treasurer” or “These documents are not relevant apropos the project.” You would never say “These documents are not apropos to the project.”
There is an adjective form of apropos, but it means “relevant,” “opportune” or (according to the NOAD) “very appropriate to a particular situation.” For example, you would not suggest apropos attire, but you could urge only apropos comments at a shareholder’s meeting — that is, comments that address the topic at hand.
And since you may as well ask my four year-old to recite the quadratic equation, better just to not waste your breath, and reserve apropos for a more appropriate time.
— Otto E. Mezzo