1) A fake friend.
2) Two people act like they're best friends, but then talk behind each other's backs constantly.
3) Uses the said 'friend' to feel better about themselves.
Observer 1: Rachael's been talking so much shit about Casey and they're supposed to be best friends?
Observer 2: That's not a best friend, that's a faux friend.
Someone who says they are your friend and is really an acquaintance.
Someone who claims to be your friend, but is never really there when you need them, doesn't return your calls or messages unless they need something, and when chatting about getting together they reply with, "yeah, let's do that sometime really soon."
Someone who claims to be your bestie, but never returns your calls or emails, unless they need something.
Someone who only wants you around when they are going through a rough time, when things are better for them they are too busy to get together or chat, that's when you realize they are a faux friend.
Someone who replies to getting together on a specific day with, "sounds good, let's do that sometime really soon."