Nope, I didn't pull it from there, but I checked and their definition is the same, so good job. Unfortunately, Merriam Webster is still not as credible globally as Collins'... So eh, dunno man.
Again, I'm not even going to start pointing out how badly you have made your arguments. To be honest, internet arguments are stupid. And you're doing everything you can to lose one. A couple things:
One, internet arguments are never won. They are usually fought by two sides who will remain completely unmoved in their opinion regardless of what supporting evidence either side has.
Generally internet arguments are won (in the eyes of the other people witnessing them) by the more well-versed of the people participating. This is stupid, but it is true; and as someone with a Linguistics degree, I can guarantee you I would run circles around you in this area if I really wanted to make you look bad or "win" this argument.
I'm just rather astounded someone can have a thought process like yours. It's simply incorrect and I can't understand it. If for some reason you feel like all sexualities are defined only by the act of sex, you can go ahead and think that. It won't make you more correct.
As far as your "counter argument" after I called you out, I'd read it, but to be honest, it wasn't an argument. If that was really the point you were trying to make it was completely non sequitur to the original statement. The original argument sprung from whether or not sexuality was a choice. Your apparent argument about not clarifying the object of attraction is completely irrelevant and unrelated. So yes, this in and of itself, is a formal fallacy.
And I read King Ace's post. It didn't add to the discussion. Rather, it brought forward the same question that was already being asked.
With this, I'm out. Try not to hurt yourself any more Neo. ;]
Oh, and also, stop capitalizing random words. It does nothing to add to your point, and actually makes your posts quite irritating to read. (Which also doesn't further how you look in a random onlooker's eyes!)