The word "full pep" refers to a high level of energy or enthusiasm. Its antonyms would be words that convey the opposite meaning, such as "lethargic", "listless", "dejected", "discouraged", "despondent", and "drained". These words indicate a lack of energy, motivation, and positive outlook. The antonyms of "full pep" can be used to describe people who are tired, depressed, or unmotivated. They may also be used to describe situations or events that are dull or uninteresting. Knowing the antonyms of "full pep" can help us better describe our feelings and experiences, and better appreciate the moments when we truly feel energized and enthusiastic.