two (or more) girls who are engaged in sexual activities with one another. they could be making out, rubbing licking and sucking each others tits, rubbing licking and fingering each others wet pussies, rubbing licking or sucking each others clits, fucking each other with a strap on or dildo, sharing a dildo/vibrator, or simply watching or helping each other get off. girl on girl is very erotic to watch and participate in.
the girls do not have to be, but usually are lesbians or bisexual.
by addy April 09, 2005