Dictionary.com
Thesaurus.com

tribadism

American  
[trib-uh-diz-uhm] / ˈtrɪb əˌdɪz əm /

noun

  1. lesbianism.


tribadism British  
/ ˈtrɪbədˌɪzəm /

noun

  1. a lesbian practice in which one partner lies on top of the other and simulates the male role in heterosexual intercourse

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of tribadism

First recorded in 1810–20; tribade + -ism