apropos

Of an appropriate or pertinent nature.

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

A particularly apropos line many will remember from this film was the closing shot of a Times editorial reading "Is There No Sense of Decency?"

By the way, incidental.

Sherlock Holmes rose and lit his pipe. "No doubt you think that you are complimenting me in comparing me to [C. Auguste] 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 [Edgar Allan] Poe appeared to imagine."

Regarding, concerning, in regard to, on the subject of

Few have the same root and branch obsession with the recent past or the avenger’s recall (‘the necessity for long memory and sarcasm in argument’, as he wrote apropos the old left intelligentsia in New York).

By the way.

Timely; at a good time.

To the purpose; appropriately.