Female to Male/ FTM- a trans person who was assigned female sex, and now lives as a man and has a masculine gender identity. This person may or may not have altered his physical body with surgery, hormones, or other modifications (e.g., voice training to develop a deeper spoken voice). FTM is an abbreviation of female to male. Generally uses masculine pronouns (e.g., “he” or “his”) or gender neutral pronouns.
Gender Fluid- someone whose gender identity and presentation are not confined to only one gender category. Gender fluid people may have dynamic or fluctuating understandings of their gender, moving between categories as feels right. For example, a gender fluid person might feel more like a man one day and more like a woman on another day, or that neither term is a good fit.
Gender Nonconforming- Someone who looks and/or behaves in ways that don’t conform to, or are atypical of, society’s expectations of how a person of that gender should look or behave. (See also this excellent article by Dr. Eric Grollman about gender conformity & gender non-conformity).
Gender Questioning- Someone who may be questioning their gender or gender identity, and/or considering other ways of experiencing or expressing their gender or gender presentation.
Gender Variant- an umbrella term that refers to anyone who, for any reason, does not have a cisgender identity (which includes the trans* umbrella). Others acknowledge issues with this term as it implies that such genders are “deviations” from a standard gender, and reinforces the “naturalness” of the two-gender system. Some prefer the terms“gender diverse” or “gender-nonconforming.”
Genderqueer- Someone who identifies outside of, or wishes to challenge, the two-gender (i.e., man/woman) system; may identify as multiple genders, a combination of genders, or “between” genders. People who use this term may feel that they are reclaiming the word “queer”, which has historically been used as a slur against gay men and women. This term is used more often by younger generations doing the “reclaiming” and less often by slightly older generations who may have personally experienced the term “queer” as a slur.
Intersex- Generally refers to someone whose chromosomes, gonads (i.e., ovaries or testes), hormonal profiles, and anatomy do not conform to the expected configurations ofeither male typical  or female typical bodies. Some intersex conditions are apparent at birth, while others are noticed around puberty or later (if ever). Some individuals no longer use the term “intersex conditions” and instead prefer “disorders of sex development.” (See ISNA.org.)
Male to Female/MTF- a trans person who was assigned male sex (likely at birth), and now lives as a woman and has a feminine gender identity. This person may or may not have altered her physical body with surgery, hormones, or other modification (e.g., voice training, electrolysis, etc). MTF is an abbreviation of “Male To Female”. Generally uses female pronouns (e.g., “she” or “her”) or gender neutral pronouns.
Neither- Not putting a label on one’s gender.
Neutrois- An umbrella term within the bigger umbrella terms of transgender or genderqueer. Includes people who do not identify within the binary gender system (i.e., man/woman). According to Neutrois.com, some common Neutrois identities include agender neither-gender, and gender-less.
Non-binary- Similar to genderqueer, this is a way of describing one’s gender as outside the two-gender (i.e., man/woman) system and/or challenging that system.
Other- Choosing to not provide a commonly recognized label to one’s gender. When used by someone to describe themselves, this may feel like a freeing way of describing (or not specifically describing) their gender. The term “other” should not be used to refer to people whose gender you can’t quite understand or place.
Pangender- “Pan” means every, or all, and this is another identity label such like genderqueer or neutrois that challenges binary gender and is inclusive of gender diverse people.
Transgender- an umbrella term that includes all people who have genders not traditionally associated with their assigned sex.  People who identify as transgender may or may not have altered their bodies through surgery and/or hormones. Some examples:
Trans Man (see FTM above); Although some people write the term as “transman” (no space between trans and man) or trans-man (note the hyphen), some advocate for a space to be included between “trans” and “man” in order to indicate that the person is a man and that the “trans” part may not be a defining characteristic or central to his identity.
Trans Woman (see MTF above) Although some people write the term as “transwoman” (no space between trans and woman) or trans-woman (note the hyphen), some advocate for a space to be included between “trans” and “woman” in order to indicate that the person is a woman and that the “trans” part may not be a defining characteristic or central to her identity.
Trans Female (see MTF above)
Trans Male (see FTM above)
Trans Person (see transgender above); another way of saying someone is a transgender person. (Note that “transgender” tends to be preferred over “transgendered”).
Trans* is an inclusive term, referring to the many ways one can transcend or even transgress gender or gender norms (e.g., it includes individuals who may identify as transgender, transsexual, gender diverse, etc). In many cases the asterisk (*) is not followed by a sex or gender term – it’s just written as Trans* - to indicate that not all trans people identify with an established sex or gender label. Another option is to write it as:
Trans*Person (see transgender above)
Other times, a sex or gender label may be used:
Trans*Female (see MTF)
Trans*Male (see FTM)
Trans*Man (see FTM)
Trans*Woman (see MTF)
Transsexual person - For many people this term indicates that a person has made lasting changes to their physical body, specifically their sexual anatomy (e.g., genitals and/or breasts or chest), through surgery. For some, the term “transsexual” is a problematic term because of its history of pathology or association with a psychological disorder. In order to get the operations necessary for sexual reassignment surgeries or gender confirming surgeries, people long needed a psychiatric diagnosis (historically, that diagnosis was “transsexualism”) and recommendations from mental health professionals. The term “transsexual” tends to be used less often by younger generations of trans persons.
Transsexual Woman – Someone who was assigned male sex at birth who has most likely transitioned (such as through surgery and/or hormones) to living as a woman.
Transsexual Man- Someone who was assigned female at birth who has most likely transitioned (such as through surgery and/or hormones) to living as a man.
Transsexual Female (see Transsexual Woman)
Transsexual Male (see Transsexual Man)
Transgender is an umbrella term which includes all people who have genders not traditionally associated with their sex at birth.  Transgender person can also be used. This may (but does not necessarily) include:
Transgender Female (see MTF)
Transgender Male (see FTM)
Transgender Man (see FTM)
Transgender Woman (see MTF)
Transmasculine- Someone assigned a female sex at birth and who identifies as masculine, but may not identify wholly as a man. Often, you’ll encounter the phrase “masculine of center” to indicate where people who identify as transmasculine see themselves in relation to other genders.
Transfeminine- Someone assigned a male sex at birth who identifies as feminine, but may not identify wholly as a woman. Often, you’ll encounter the phrase “feminine of center” to indicate where people who identify as transfeminine see themselves in relation to other genders.
Two-spirit- This term likely originated with the Zuni tribe of North America, though two-spirit persons have been documented in numerous tribes. Native Americans, who have both masculine and feminine characteristics and presentations, have distinct roles in their tribes, and they are seen as a third gender. (Recently, Germany  and Nepal adopted a third gender option for citizens to select).