Please tear this apart if you have time?
This terminology is not definitive and a great deal of the complexity of identification is missing (especially in subcultures and identities that recognize the meeting place of sexual behavior and race). However, it is a collection of commonly-used definitions and differentiations within the lesbian, gay, bisexual, transgendered, queer, questioning, and allied movement(s).
Allied/Ally: Someone who confronts heterosexism, homophobia, biphobia, transphobia, heterosexual and genderstraight privilege in themselves and others; a concern for the wellbeing of lesbian, gay, bisexual, trans, and intersex people; and a belief that heterosexism, homophobia, biphobia and transphobia are social justice issues.
Asexual: A person who is not sexually attracted to anyone or does not have a sexual orientation.
Bisexual: Those whose sexual, emotional, or mental attractions are oriented toward men, women, and (possibly) those identifying as otherwise sexed. This is an identity label and not all those who meet these characteristics will identify as bisexual.
Cisgendered: A concept which labels persons who are not transgendered as something other than simply "normal". This provides a name for a gender identity or performance in a gender role that society considers matching or being appropriate for one's sex. The term was developed as a way to shift the focus off of a marginalized group, by defining not only the minority group but also the majority.
Coming Out: May refer to the process by which one accepts one’s own sexuality, gender identity, or status as an intersexed person (to “come out” to oneself). May also refer to the process by which one shares one’s sexuality, gender identity, or intersexed status with others (to “come out” to friends, etc.). This can be a continual, life-long process.
Gay: Men whose sexual, emotional, or mental attractions are primarily or entirely oriented toward other men. This is an identity label and not all men who meet these characteristics will identify as gay.
Gender: One’s expressions of masculinity, femininity or androgyny in words, persons, organisms, or characteristics.
Genderqueer: A gender diverse person whose gender identity is neither male nor female, is between or beyond genders, or is some combination of genders.
Heterosexism: The belief that heterosexuality is a superior way to live and the set of privileges received by heterosexual people because of their sexual orientation.
Heterosexual: Often used to refer to those people whose sexual, emotional, or mental attractions primarily or entirely oriented toward people not sharing their same sex characteristics. This is a term used by some as a reference to personal identity.
Homphobia: The irrational fear of homosexuality resulting in prejudice and discrimination towards LGBTQQ people.
Homosexual: Often used to refer to those people who sexual, emotional, or mental attractions primarily or entirely oriented toward people sharing their same sex characteristics. It is a medicalized term, originating in the psychological institution as a way of diagnosing what was (formerly) seen as an illness. It is not a term that most people use as an identity and can be found profoundly offensive by many.
In the Closet: A queer person who will not or cannot disclose their sex, sexuality, sexual orientation or gender identity to their friends, family, co-workers, or society. Also known as ‘Downlow” or ‘D/L.’
Intersex: A general term used for a variety of conditions in which a person is born with a reproductive or sexual anatomy that doesn’t seem to fit the typical definitions of female or male. For example, a person might be born appearing to be female on the outside, but having mostly male-typical anatomy on the inside. A person may also be born with genitals that seem to be in-between the usual male and female types—for example, a girl may be born with a noticeably large clitoris, or lacking a vaginal opening. A person may also be born with mosaic genetics, so that some of her cells have XX chromosomes and some of them have XY.
Lesbian: Women whose sexual, emotional, or mental attractions are primarily or entirely oriented toward other women. This is an identity label and not all women who meet these characteristics will identify as lesbians.
Men who have sex with men: A term used by the Center for Disease Control to identify the category of men who are sexually active with other men, regardless of their self-identity. This term exclusively refers to behavior, not identity.
Queer: 1. An umbrella term which embraces a matrix of sexual preferences, orientations, and habits of the not-exclusively- heterosexual-and-monogamous majority. Queer includes lesbians, gay men, bisexuals, transpeople, intersex persons, the radical sex communities, and other sexually transgressive folk. 2. Can be used sexual orientation label as a way of acknowledging that there are more than two genders to be attracted to, or as a way of stating orientation without having to state who they are attracted to. 3. A reclaimed word that was formerly used solely as a slur but that has been semantically overturned by members of the maligned group, who use it as a term of defiant pride. Nevertheless, some people to whom this term might apply still hold ‘queer’ as an insult, and its use by heterosexuals is often considered offensive. Extreme caution must be taken concerning their use when one is not a member of the group.
Questioning: A person in the process of actively exploring sexual identity.
Sex: Sex is what a person is physically born with - hormones, chromosomes, genitals, reproductive organs, secondary sex characteristics. Male and female are sex words, and they're our society's binary categories for sex.
Sexual Orientation: the deep-seated direction of one’s sexual attraction, which is based on feelings and not behaviors. This is a term preferred over "sexual preference" when referring to sexual/affectional relationships
Transgender: A person who identifies as a member of a gender other than that expected based on anatomical sex. Sexual orientation varies and is not dependent on gender identity.
Transsexual: A person who identifies psychologically as a gender/sex other than the one to which they were assigned at birth. Transsexuals often wish to transform their bodies hormonally and surgically to match their inner sense of gender/sex.
Transvestite: Someone who dresses in clothing generally identified with the opposite gender/sex. The majority of transvestites are heterosexual males who derive pleasure from dressing in “women’s clothing”. (The preferred term is ‘cross-dresser,’ but the term ‘transvestite’ is still used in a positive sense
Two-Spirited: Native persons who have attributes of both genders, have distinct gender and social roles in their tribes, and are often involved with mystical rituals (shamans). Their dress is usually mixture of male and female articles and they are seen as a separate or third gender.
Ze / Hir: Alternate pronouns that are gender neutral and preferred by some gender diverse persons. Pronounced /zee/ and /here,/ they replace “he”/”she” and “his”/”hers” respectively.
Definitions taken from and adapted from Stanford University’s Anti-Homophobia Workshop Outline, the Intersex Society of North America, and the LGBT Resource Center at UC Riverside, the American Psychological Association, and the postqueer community on LiveJournal.