Acquaintance (noun)

1. A person one knows slightly, but who is not a close friend.
2. A person one has met but does not know well.

Origin:

Late middle english: from old french aquainte, from aquerre "get to know", from latin acquirere.

Examples:

1. I met her at the party, she's just an acquaintance.
2. He is an acquaintance of mine from work.
3. She is an acquaintance of my sister's.
4. The acquaintance became a close friend over time.
5. They are just acquaintances, they have not met more than a few times.