Cissexual and Cisgender are terms for non-transsexual people, whose assigned gender matches their assigned sex.
The term sex refers to biological maleness or femaleness. Males have XY chromosomes. Females have XX chromosomes. Sex is determined the instant a woman's egg is fertilized by a man's sperm. If an X sperm fertilizes an X egg, the fetus will be female. If a Y sperm fertilizes the X egg, the fetus will be male. Some people also have conditions of "sex differentiation" or "intersex" conditions that can affect this typical pattern.
The term gender refers to the behavioral, cultural, and psychological traits typically associated with one sex. Babies are usually assigned a male gender at birth if they have a penis, and a female gender if they have a vulva. Gender identity is how someone feels about their gender assignment.
A person who identifies as transgender," generally feels that their sex and gender do not completely match, and so would not generally identify as cissexual or cisgender.
