cis- Look up cis- at Dictionary.com
word-forming element meaning “on the near side of, on this side,” from Latin preposition cis “on this side” (in reference to place or time), related to citra (adv.) “on this side,” from PIE *ki-s, from root *ko- “this” (cognates: Old Church Slavonic si, Lithuanian šis, Hittite ki “this,” Old English hider, Gothic hidre “hither;” see he). Opposed to trans- or ultra-. Originally only of place, sometimes 19c. of time; 21c. of life situations (such as cis-gender, by 2011).
Cisgender has its origin in the Latin-derived prefix cis-, meaning “on this side of,” which is an antonym for the Latin-derived prefix trans-, meaning “across from” or “on the other side of”. This usage can be seen in the cis-trans distinction in chemistry, the cis-trans or complementation test in genetics, in Ciscaucasia (from the Russian perspective) and in the ancient Roman term Cisalpine Gaul (i.e., “Gaul on this side of the Alps”). In the case of gender, cis- is used to refer to the alignment of gender identity with assigned sex.
One of these days I’m going to either write or do a video that undoes the blurred lines of Feminist language.