'Ellos,
Here's me pretending this'll actually go somewhere constructive. Using Kulindhar's post for leaping.
Bisexual means you're attracted to, i.e. turned on by, at least some of the male population and some of the female population. That's the scientific aspect of it: your actual orientation.
Language mutates, including definitions. The dictionary is usually several decades out of date at any given time which means some of the words are
also out of date. (which on a personal note, pisses me the fuck off). Definitions shift a bit because society and culture changes. It's usually a gradual shift and it leaves a lot of people going "Nooooooo..........." because people as a whole loath change. Which is some damn amount of irony considering human adaptability. Eh, no one claimed adaptation to be enjoyable, I suppose. Anyway, language = surprisingly fluid. I know several definitions of bisexual and the people in the bisexual community that I'm familiar with use them. It isn't a particularly small community, either, considering I live in a city. The old definition wasn't erased, it's just been...added to for clarity's sake.
The scientific aspect includes the general five orientations, (asexual, homosexual, bisexual, pansexual, heterosexual). And sapiosexual has been getting counced around, some people are attracted to nothing but knowledge, although they're probably rare and that particular grouping tends to be full of people who think being attracted to knowledge is the same as
having knowledge. Incredibly erroneous assumption. In other words a lot of them aren't actually attracted to knowledge, just the appearance of someone agreeing with their opinions at length. Since knowledge doesn't equal agreement of opinion I write most of 'em off, as it were. Actually, I'd probably just consider that a fetish since orientation in our culture revolves on physical sex and/or gender. Some other cultures
just revolve on gender, although most of those that I'm aware of are nomadic and hence, not fond of outsiders.
I
didn't include the orientations that are defined via the culture+physical/biology mix in other places (because they're rarely separate in culture, in fact I can't think of any culture that totally separates them,
including ours; but for simplicity I only listed the five 'major' ones in ours. In ours being the key word, unfortunately). I can't list the great bulk of the others because there's too damned many and I'm not even familiar with half of them. A lot of other cultures conceptualize sex and gender differently. In some they're really
not the same thing, so who would be considered straight isn't transferable to who 'we' would consider straight. Not everyone is quite so fixated on defining sex and gender via dangly bits. Mind you, only some dangly bits apparently count. And only in a certain manner with a checklist of characteristics and/or experiences that varies depending on who you ask. /snark And it really does vary a surprising amount, at least in my experience.
So, I've got yet another wrench to toss into this conversation - what about the people who are turned on by sex itself instead of gender or physical sex? Not talking about fetishes, but sex itself. I think Bankside mentioned that in another thread. I know several people besides myself like that, it's why my profile says pansexual on it since there isn't a word for it. It isn't "I'm possibly attracted to everyone regardless of gender", it's "I like sex for itself, are we compatible?"
Then there's straight people who can (and do) participate in various aspects of bdsm with the same gender and it's the fetish that gets them off, not the gender of their partner. Though the gender might matter depending on the fetish involved. That said, they're actually, physically attracted to the opposite sex, the physicality of men doesn't turn 'em on. There's...a hell of a lot of them, actually. A damn surprising amount, now that I think about it. Could do a paper on this, hrm. Point I was trying to make was most people on this board would label them bisexual because they got off (happily, even) with men, despite those straight guys having no interest in dick. Contrarywise, there's women who do the same thing.
People like to think it's clear cut, but mostly I don't believe it is. Or at least, there's a very large portion of humanity that doesn't equate gay with liking identical genitalia as its
sole definition. The word sole here being key, I think. Which, hello various cultures, of which the usa is a melting pot. Difficult to pick through language wise for understanding concepts, I have to say, and several concepts aren't really transferable between cultures for understanding. Which is something a lot of people find odd if they aren't familiar with sociology and culture. Frustrates me all to hell when learning, but can't do anything about it, really.
Anyway, wandered off on a related tangant. Point being it's nigh to impossible to identify bisexual, straight, and gay when gender and sex need to be given definitions
first. People love to reference the scientific definition of sex but most of them aren't aware it's actually a checklist and that you don't need (and often cannot) check all the boxes. Few people have their chromosomes tested, for instance, and quite a few chromosome differences go,l if not unnoticed, at least unremarked upon and considered a variation in the way people look and various possible disabilities. It's a 'which side has more ticks' guessing game and most doctors stop at a glance between the legs. So basically, one tick is given when the actual designation of sex is decided by various things that have little to do with how genitalia dangles.
Roughly, everyone's doctor guessed by the quickest route possible.
Since the scientific definition of sex compiles several things and those things can vary - a nice tight box based on the assumption that genitalia equals the scientific definition of how sex is actually assigned (vs how a birthing doctor does it) isn't doable intellectually for fine-tuned conversation. There's only a half-assed at best definition of sexed-based orientation when someone doesn't include a complete definition of how sex is assigned. Let alone how gender is performed culturally. People are clinging to a guess with both hands and using that guess to describe little bits of sexuality while trying to pretend one bit is the whole basis and everything else is merely a quirk. Y'don't have to change the definition of your sexuality just because you acknowledge someone else's. It would be humorous if it weren't so frustrating.
I brought that up because sexuality as it's used in this discussion is mostly based on assumed sex. While totally ignoring the cultural aspects of identifying sex, which is no mean feat considering one of our cultural quirks is how most people get that 'm' box checked. And people who are ignoring how their culture is influencing their perception of the base definitions re; sex and gender can't really have a discussion about it.
So a
general definition of bisexual could be made, sure, so long as everyone is on the same page. But if people were generally on the same page there wouldn't be, ah, 16 pages of this, for instance. Possibly 17, I usually don't check the numbers. And we're just discussing different ways people come to a bisexual label, no one has really conversed about how those labels are made on a deeper level.
Identity is more subjective; it involves both attraction/desire and choice. But if you identify as gay, yet still get turned on by at least some gals, then your orientation is bi, and honesty dictates telling your BF.
When someone asks or tells someone their sexuality they lump both orientation and identity into the same word. Most people don't bother to separate them in their heads, assuming that they can be separated conceptually for the individual (I've met a few who can't). Most people are
not introspective, though. Orientation also seems to be formed
somewhat by identity which is informed partly by orientation and social...blah blah blah. Big circular mess where parts inform other parts as you grow. Comes to nature vs nurture and the answer, I believe, is both.
I see no reason to make five thousand or however many differing definitions of sexuality. What I do see is a need to include others' definitions and why they've defined a word in a particular manner when having a discussion on who fucks who and why.
I agree with one of the previous posters. If someone finds they're attracted to both sexes and chooses to date only one, I don't find that to be any different between someone dating a guy and not telling his whipcord-thin, tattoo wearing boyfriend that he's also attracted to large guys with spectacles. Either way he's not planning on fucking the large guy with spectacles. Or whatever woman happens to catch his attention. Which attraction is most likely low, otherwise he probably wouldn't've bothered identifying as gay in the first place.
That said I'm a big fan of sharing in relationships - including sharing definitions of sexuality with your partner. So either way a partner would be aware eventually. He could always say he's functionally gay as that seems to be as accurate as anything.
-And yes, I know, I wandered into definitions of sex and gender, but I honestly don't believe people can discuss sexuality without knowing what people
mean by sex and gender. Because few people mean quite the same thing when they mention it. Bring in anyone that isn't a duplicate of their body and/or culture and suddenly there's a tizzy. If they meant the same thing as each other I'd think most people would agree on others' identity and orientation definitions - but they don't.
I used your post as a jumping-off point (for the most part) so my apologies if there's confusion. I don't mean to imply that my writing is in direct response to beliefs you haven't posted. I tend to write like an elementary book partly in the hopes of not confusing people because the concepts themselves are....complex to say the least, an no-one wishes to read a detailed tome but goddamn they generally take it the wrong way anyway.

In other words, I'm at the fuck 'em stage regarding length and content. But thanks for jumping-off point!