Related terms include trans*, gender binary, intersex, pansexual, gender spectrum.
"Jordan has a nonbinary gender identity because ze has never felt like a man or a woman."
A nonbinary gender identity is one that does not fall within standard categorizations of male/female or man/woman. A nonbinary person not self-identify as a man or a woman-- or identifies sometimes as a man and sometimes as a woman-- thereby falling completely outside the typical gender binary.
Nonbinary people can be AFAB, AMAB, or biologically intersex, and may have any sexual orientation. They are generally considered to fall under the trans* umbrella. However, nonbinary individuals differ from most transgender people in that they do not explicitly self-identify as men or women. Nonbinary people may or may not have a desire to physically transition through interventions such as HRT and SRS.
The use of gendered language can be complicated for nonbinary people. While some nonbinary people use the pronouns he and she, others avoid binary language and prefer to be referred to with other preferred pronouns such as ze, sie, hir, co, ey, or singular "they, or by avoiding pronouns altogether. Some nonbinary people also prefer the use of gender-neutral identifying nouns, such as "spouse" instead of husband or wife and "sibling" instead of brother or sister. They may also use "Mx." as a substitute for Mr., Miss, Mrs., or Ms.
Nonbinary identities include genderqueer, genderfluid, agender, gender neutral, genderless, bigender, trigender, pangender, neutrois, two-spirit, third gender, and androgyne.