If something is dominating, that means it has a powerful and commanding position. If your team is dominating on the basketball court, you're not only winning, you're outplaying your opponents.
Dominating comes from the root word dominate, which comes from the Latin word dominari, meaning "to rule, to govern." When you're a dominating presence, you're self-assured and clearly in charge of your environment — possibly even to the point of being bossy. An object can be dominating too, such as that tall church in the distance that's dominating the landscape.