acquaintance

Short definition from Wiktionary

Noun

1. 1
   A state of being acquainted with a person; originally indicating friendship, intimacy, but now suggesting a slight knowledge less deep than that of friendship; acquaintanceship.
2. 2
   A person or persons with whom one is acquainted.
3. 3
   Such people collectively; one's circle of acquaintances (with plural concord).
4. 4
   Personal knowledge (with a specific subject etc.).