Adjective

1. Of an appropriate or pertinent nature.
   • 1877, Jules Verne, translated by Frederick Amadeus Malleson, Journey into the Interior of the Earth, Chapter VI,

     Nothing easier. I received not long ago a map from my friend, Augustus Petermann, at Leipzig. Nothing could be more apropos.

Preposition

1. Regarding or concerning.

   Apropos the return home of the body of old King Nicholas of Montenegro ('Communists allow burial of Montenegro's last king', 2 October): King Alexander of Yugoslavia was his grandson, not his son-in-law.

Quotations

Sherlock Holmes rose and lit his pipe. “No doubt you think
that you are complimenting me in comparing me to Dupin,”
he observed. “Now, in my opinion, Dupin was a very inferior
fellow. That trick of his of breaking in on his friends'
thoughts with an apropos remark after a quarter of an hour's
silence is really very showy and superficial. He had some
analytical genius, no doubt; but he was by no means such
a phenomenon as Poe appeared to imagine.”

—Sir Arthur Conan Doyle in A Study in Scarlet