FORMAL
used to introduce something which is related to or connected with something that has just been said I had a letter from Sally yesterday — apropos (of) which, did you send her that article?
Apropos what you said yesterday, I think you made the right decision.
• a very steep side of a cliff or a mountain The film opens with a shot of a climber dangling from a precipice.
• a dangerous situation which could lead to harm or failure This latest tax increase may push many small companies over the financial precipice.