WordWeb Online

1. Of an appropriate or pertinent nature

1. At an opportune time
   "your letter arrived apropos"
   - seasonably, timely, well-timed
    
2. Introducing a different topic; in point of fact
   - by the way, by the bye, incidentally

See also: apposite, appropriate, appropriateness, apt, pertinent

Antonym: malapropos

Encyclopedia: Apropos