Definition of "tribadism"

Things changed when Théophile Gautier made tribadism a fashionable feature of French decadence, and Baudelaire reminded the world that it all started on Lesbos.

2004 February 2, Emily Wilson, “Lady of Lesbos”, in The Guardian‎

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.

1908, Medical Council: Volume 13, page 12

In Bali […] homosexuality is almost as common among women as among men, though it is more secretly exercised; the methods of gratification adopted are either digital or lingual, or else by bringing the parts together (tribadism).

1927, Havelock Ellis, Studies in the Psychology of Sex‎, 3rd edition, volume 2