1. The capacity or power to do work or cause change; physical or mental strength
She has a lot of energy and enthusiasm for her work.
Ela tem muita energia e entusiasmo pelo seu trabalho.
2. Power derived from the utilization of physical or chemical resources
Solar energy is a renewable resource.
A energia solar é um recurso renovável.
4. In physics, the capacity to do work, measured in joules
Kinetic energy depends on mass and velocity.
A energia cinética depende da massa e da velocidade.