When a cis person explains something to a trans person that they already know or explains trans issues to a trans person, when they (the cis person) themselves don't know what they're talking about, because well they're cis and don't experience trans issues.
"I'm not transphobic, transphobia is the fear of trans people, and being trans gender is due to a mental disorder called gender dysphoria"
"You're taking the word transphobic out of context, being trans isn't a mental illness and the treatment for gender dysphoria is transitioning, you're such a cis-splainer, stop cis-splaning"
by DSMbomb October 30, 2021
Get the Cis-splaning mug.