If your basketball team is undefeated, you could say that it was able to dominate the competition. To dominate means to be in control or have the power to defeat.
Dominate is related to the word domain — which means home. While these words may not seem all that similar, when you are the master of a home or thing, you dominate it. If you get angry, it is wise to not let your feelings dominate you or your actions. Dominate can also mean to be most prominent. If in the woods around your house, oak trees are the most common, you could say that "oak trees dominate the forest."