Exuberance in nature is defined by lush, profuse, riotous growth; it is an overflowing, opulent, and copious abundance. Early uses of "exuberance" in English were mostly in the context of descriptions of nature, of profuse crops or of kinetic natural phenomena such as shooting stars, sulfur springs, and waterfalls. . . . Over time, the definition of "exuberance" evolved; where it had focused on the fertility of nature, it began to center on the fertility and force of human energy and mood. . . In our time, "exuberance" usually denotes a mood or temperament of joyfulness, ebullience, and high spirits, a state of overflowing energy and delight. It is more energetic than joy and enthusiasm but less intense, although of longer duration, than ecstasy.

Kay Redfield Jamison, Exuberance