Typically used in terms like cisgender or cissexual. Cisgender people are those who remain their gender observed at birth by the doctor, cissexual refers to people who are attracted to those who are their birth gender. Can also be used as an acronym like "Comfortable In Self" which can imply those who are choosing a different gender than at birth (transgender) aren't comfortable with their existing self prior to transitioning which is true given gender dysphoria as a mental illness.
This guy is cis, he was born a male and chose to remain a male rather than transition to another gender.
by thepcwiz101 March 11, 2024
Get the cismug. 
by tittylover69 June 17, 2021
Get the cis momentmug. Cis-attraction is attraction to individual(s) on the basis that their gender identity aligns with the sex (or gender) they were assigned at birth. A cis-attracted person can be hetero-, homo-, or bi-sexual. All that matters is that they are attracted to cis-persons—regardless of whether or not that person is male (a man), female (a woman), intersex, or was assigned non-binary (X) at birth.
by lordcapo November 29, 2020
Get the Cis-attractedmug.