Domination: to have control over someone or something.
Very easy definition, no?
In a Domestic Discipline lifestyle, that definition is so generalized and simplified, it's rendered almost meaningless.
Husband is my Dom. He has authority over me. Certainly, when we are in the bedroom, he has control over me.
But in many ways, I have control over him, too. I can make his life easy--or I can make his life hard. I can submit quickly, or...not. I can be fun, experimental, enthusiastic, and kind, or I can just go through the motions of being a "good" wife without really putting any effort into what that means. And the differences between the two are striking.
This is what domination means for us, and while I can only talk for us, I think it's basically true in any BDSM relationship: it means having authority over someone that you would otherwise think of as an equal. It means being granted control over the other person's behaviors for whatever time and extent has been agreed upon, but once that time is up, the two of you stand on equal ground again.
There is no inherent superiority involved.
This, in my humble opinion, is a very important distinction. There is a difference between a Dom who believes a sub's submission is a power to be taken when offered, a privilege, something he must care for and return when it's time, and a "Dom" who thinks submission is is his right to take whenever he wants, like an apple fallen off the tree, on the grounds of his natural superiority.
One is a good Dom, or at least holds the potential to be one; the other is just a misogynistic asshole. Unfortunately, there are a lot of misogynistic assholes out there posing as "Doms."
A Dom will be a gentleman. A Dom will look you in the eyes, shake your hand, and greet you respectfully. A Dom will send polite emails when corresponding. A Dom will listen to what you have to say, accept what is important to you as important to him, too (no matter what your reasoning for it), and hold your thoughts and feelings and opinions dear. A Dom will make no assumptions, because he knows he has no right to.
A misogynistic asshole posing as a Dom will, very quickly, show his crassness and insensitivity. He might send you a message saying something to the effect of, "hey baby, want me to tie you up and fuck your face?" Just to see the kind of reaction he gets. He will not care about your desires, or your limits, because all he considers are his own. To him, his wants are always going to be more important than yours, because in his mind, the two of you are not equal.
Subs who are prone to low self-esteem should especially be wary of these kinds of "Doms." It is the job of the Dom to bring the sub up, not kick her further down. One sign of a good Dom is a sub who believes, with all her heart, she is becoming a better person through his help and guidance.
This is why I firmly believe Domestic Discipline should never include coercion, or belittlement, or any kind of mental cruelty that makes one person feel less than the other. Because that's not discipline anymore: that's just simple malevolence, and doesn't belong in any relationship, kinky or otherwise.