When did cisgender become a word? I don’t think that it is more than 5 years old, and I still don’t know what it really means — gobbledegook!
“Cisgender” basically means “normal”. It indicates that your gender matches your sex.
In the science of molecules, “CIS“ and “TRANS“ relate to the mirror images of a complex molecule, sort of like left-hand and right-hand versions.
The LGBT community started calling normal people “cisgender“ to avoid having to admit that they themselves were abnormal.
It means “sane”.
It is Newspeak, from 1984.