Cisgender

Cisgender (often shortened to cis) is the opposite of transgender, meaning someone who identifies with the gender they were assigned at birth.

Etymology
Cis comes from the Latin prefix meaning 'on the same side' as in the cis-trans distinction in chemistry. The origin of the term is credited to Carl Buijs who proposed the term in 1995, although the word has been used on the internet before 1995 Carl Buijs is the first recorded source to define the term. It's possible that the term was independently coined.