Cis means near side and trans means across. They're latin prefixes, for example: Transalpine Gaul and Cisalpine Gaul refers to designated regions.
So, anyway, in gender terms
Trans means someone who has crossed to another gender, so a trans woman would be someone who wasn't a woman before.
Cis means someone who hasn't, so a Cis woman is someone who has always been a woman.
Although, I don't know any transgender people, or really anyone who has an opinion on it. So I am not actually sure if I have the accurate definitions here.
I describe myself as a little dose of toxic masculinity.