Agender: Someone who feels neither male or female.
CIS Gender: A person who was born as a female and identifies as a female or a person who was born as a mal and identifies as a male.
FTM: A person who was born as a female, but wants to or is transitioning to a male.
Gender fluid: Much like sexuality, gender can be fluid. People who Identify as gender fluid often switch their gender, i.e. one could identify as a girl one day, as a boy the next, and neither the third.
Gender Queer: A term for those who don't identify with the gender they were born as.
MTF: A person who was born as a male, but wants to or is transitioning to a female.
Transexual: Someone in the process of changing your physical body to the opposite sex.
Transgender/Trans: One whose gender identity is the opposite of their physical sex.
Transvestite: Someone who dresses as or takes on the "traditional" gender roles of te opposite sex.
Two Spirited: A Native American term where it is believed that two spirits live in one body, the spirit of a male and the spirit of a female.