Which word refers to being cheerful and full of energy?

The term that best conveys the idea of being cheerful and full of energy is "ebullient." This word describes a state of enthusiasm, excitement, and exuberance, often associated with a lively and animated demeanor. In various contexts, you might find "ebullient" used to illustrate individuals who are not just happy but radiate a vibrant energy that is contagious to those around them.

In contrast, "pallid" indicates something that is pale or lacking in color, often used to describe a lack of vitality or energy. "Nuances" refers to subtle differences or distinctions in meaning or expression, which does not relate to cheerfulness or energy. "Atrophies" pertains to the decrease in size or wasting away of a body part or tissue due to lack of use or injury, suggesting a deterioration rather than an exuberant state. Hence, "ebullient" distinctly captures the essence of cheerfulness and vibrant energy.