Your argument was that the union gives you more power via the collective bargaining, but that you still retain your individual bargaining power.

You don't.

If you were to come to my company and try to convince me to start a union, I'd say "thanks, but no thanks".

Just now, you are trying to convince me that I'd be retaining my individual bargaining power, if I accept to use a different definition.

Well, I was born in a Communist country, where they were fond of changing definitions. We were free to vote for whomever we wanted, as long as it was someone on the list presented to us. We had no say in who was on that list. Of course, we were free to not vote at all, right? Boys had to do mandatory military service. You know how they were called when they were conscripted? "Volunteers". That was the official name.

So, yes, I'm used to the tactic of changing definitions. But if you are serious about presenting an argument, you should no use this tactic.