2004, Emily Wilson, "Lady of Lesbos", The Guardian, 2 Feb 04:
Things changed when Théophile Gautier made tribadism a fashionable feature of French decadence, and Baudelaire reminded the world that it all started on Lesbos.
Specifically, a form of lesbian intercourse involving the rubbing together of two partners' vulvae.
1908, Medical Council: Volume 13 (page 12)
The Lesbian is the analogue among women of Persian love among men, and this perversion takes place in two ways, either by friction of the two female bodies, known as tribadism, or by the tongue, designated as cunnilinguism.