The term "sexual orientation" is never defined. Not in public discourse, not in law. Yet there is law banning discrimination on the basis of "sexual orientation" -- whatever that is. How absurd.
Even the participants in the GLBT counterculture don't agree on definitions, or even terminology. New vocabulary is added monthly, it seems, and definitions are changed constantly. For instance, look at these newly-minted definitions in GLSEN's "Day of Silence" organizing manual, being disseminated to young people across the country. (GLSEN = Gay, Lesbian, & Straight Education Network.)
So you thought you knew what "gay" or "lesbian" meant? Check again. Note that, according to GLSEN, the concept of reality-based or biologically-based gender is obsolete. Gender confusion is the new order! And note the new "spiritual" component claimed for GLBT sexuality. (Interestingly, whether these sexualities are inborn or learned is sidestepped in these definitions.)
Sexual orientation - The preferred term used when referring to an individual's physical, emotional, romantic, and/or spiritual attraction to another person.
Gay - A term used to describe one who identifies as a man and who is attracted to other male-identified people.
Lesbian - Refers to a woman-identified person who is attracted to other women-identified persons.
Bisexual - A term used in describing an individual who expresses attraction for males and females. [Is bisexuality inborn? Did they mean to say the attraction is to "male- and female-identifying people"?]
Queer - Terms [sic] used to describe persons who are not heterosexual [or heterosexual identifying?] because of its gender-neutrality and its implication of social non-conformity.
Transgender - This term loosely [sic] refers to people who do not identify with the gender roles assigned to them by society based on the [sic] biological sex. Transgender is also used as an umbrella term for all those who do not conform to "traditional" notions of gender expression and includes people who identify as transsexual, or as a drag queen/king.