Courtesy of Trans Student Education Resources (http://www.transstudent.org/definitions)
Transgender/Trans: An umbrella term for people whose gender identity differs from the sex they were assigned at birth. The term transgender is not indicative of gender expression, sexual orientation, hormonal makeup, physical anatomy, or how one is perceived in daily life. Note that transgender does not have an “ed” at the end.
Gender Identity: One’s internal sense of being male, female, neither of these, both, or other gender(s). Everyone has a gender identity, including you. For transgender people, their sex assigned at birth and their gender identity are not necessarily the same.
Asexual: The lack of a sexual attraction, and one identifying with this orientation. This may be used as an umbrella term for other emotional attractions such as demisexual.
Bigender: Refers to those who identify as two genders. Can also identify as multigender (identifying as two or more genders). Do not confuse this term with Two-Spirit, which is specifically associated with Native American and First Nations cultures.
Binary: Used as an adjective to describe the genders female/male or woman/man. Since the binary genders are the only ones recognized by general society as being legitimate, they enjoy an (unfairly) privileged status.
Genderqueer: An identity commonly used by people who do not identify or express their gender within the gender binary. Those who identify as genderqueer may identify as neither male nor female, may see themselves as outside of or in between the binary gender boxes, or may simply feel restricted by gender labels. Many genderqueer people are cisgender and identify with it as an aesthetic. Not everyone who identifies as genderqueer identifies as trans.
Cis(gender): Adjective that means “identifies as their sex assigned at birth” derived from the Latin word meaning “on the same side.” A cisgender/cis person is not transgender. “Cisgender” does not indicate biology, gender expression, or sexuality/sexual orientation. In discussions regarding trans issues, one would differentiate between women who are trans and women who aren’t by saying trans women and cis women. Cis is not a “fake” word and is not a slur. Note that cisgender does not have an “ed” at the end.
Trans Woman / Trans Man: Trans woman generally describes someone assigned male at birth who identifies as a woman. This individual may or may not actively identify as trans. It is grammatically and definitionally correct to include a space between trans and woman. The same concept applies to trans men. Often it is good just to use woman or man.
Sometimes trans women identify as male-to-female (also MTF, M2F, or trans feminine) and sometimes trans men identify as female-to-male (also FTM, F2M, or trans masculine). Please ask before identifying someone. Use the term and pronouns preferred by the individual.