A lesbian friend. It could be between two lesbians that aren't dating and a lesbian and a male. Uncommonly used between a lesbian a straight female friend.
Lesbian 1: Hey girly, how are you and Amanda?
Lesbian 2: Wonderful, it's so great being able to talk to my lesbuddy :)
Dude 1: Hey, are you going out with that girl?
Dude 2: Pssh, naw, she's just my lesbuddy.
Straight Girl 1: Hey, you aren't turning gay on us, are you? You hang out with that lesbian Kim everyday.
Straight Girl 2: No, of course not. I completely trust my lesbuddy