The word "sprightful" is an adjective that means "full of spirit or energy." Some antonyms for this word include "lethargic," "dull," "dreary," "listless," and "inactive." These words convey the opposite meaning of what "sprightful" stands for. "Lethargic" implies a lack of energy or enthusiasm; "dull" suggests a lack of excitement or interest; "dreary" describes something that is dull and depressing, "listless" implies a lack of enthusiasm and "inactive" means without any kind of movement. When we are feeling uninspired or lacking in energy, these words might better describe our state of being.