Dictionary definitions exist and seem official, but we are not required to use words as they are defined. Yes, it is helpful to have a generally understood definition because we want to communicate with other people (and helpful when a surgeon needs to know which organ to do a procedure on or something important like that) but definitions are absolutely not set in stone.
In reality, I, and you, hold the power to redefine words particularly when it comes to how we talk to, about and for ourselves. We can always re-create the meaning to fit what we want to make of it. We have the ability to use our awareness to deconstruct any word and flip-flop it to frame it in a way that works for us. Maybe the definition of it was never created with us (e.g., BIPOC, LGBTQIA+, women, person with a disability, etc.) in mind.
Words, in themselves, mean nothing. The power always lie with the ones who think and speak them.