Quote from American Heritage Dictionary:

"Vigor or power in action, or the capacity for action. Vitality and intensity."

Description:

The Serplion of ENERGY has mounted the pyramid in triumph, its great tail spiraling all three levels. It holds the SUN in its mouth, the Fifth future SUN, symbolizing that already this SUN is contained in a higher dimension of energy. This is a most powerful pure Trump, enriching and harmonious, A man and woman in a Masonic position, right hands clasped in brotherhood, left hands laid on shoulders, signifies that the masculine and feminine energies are sill an undivided One. They just are. ENERGY's tail encircles them, protecting them from the zenith of power.

Interpreted use:

More success than even an optimistic person could expect. Steady balance between thinking and feeling functions.

Reversed (card received upside down):

Danger of non-movement through egocentricity. Hubris (excessive confidence and arrogance).