The cougar is the largest cat in North America. They are both solitary and territorial, not to mention excellent hunters. They will sit for hours just watching their prey, waiting to ambush it. Cougars are good mothers and represent power, the feminine, intuition, and strength (that of a female in defense of her young). Cougar represents leadership and taking charge of one’s life and circumstances in the most effective way. Cougar teaches decisiveness and imparts resolve, like the great hunter persevering and waiting for the perfect moment to strike. Yet cougars are easily threatened, and thus quick to attack. This is a perfect example of their good mothering qualities: females with children are very protective and quick to lash out when they feel their offspring are in danger.
In addition to these things, the cougar stands for leadership and assertiveness, because it is such a large animal.
Information from Ted Andrews's Animal-Speak, Jessica Dawn Palmer's Animal Wisdom, and Steven D. Farmer's Power Animals.