Tribbing
Tribbing or scissoring (Tribidism - the wikipedia page is fascinating). The scissoring position, which involves the partners interlocking their legs in a position similar to the shape of scissors and pressing their vulvas together, tribadism may involve a missionary position, a woman on top position, a doggy style position or others.
Our criteria for inclusions
We consider "tribbing" to be where both models' vulvas are touching. One model rubbing their vulva against a different part of another model (or, an object) we consider "humping" (or, "frottage"). both are super-sexy, but we separated them for the purists!