Antonyms for the word "peppiness" refer to its opposite, which is dullness or lethargy. Some of the antonyms for this word include weariness, sluggishness, apathy, and lethargy. These words paint a picture of a lack of energy, enthusiasm, or motivation. Other antonyms that can be associated with "peppiness" in terms of mood and personality are somberness, sadness, and depression. These words reflect the absence of the positive, upbeat feelings that someone who is peppy might experience. Overall, the antonyms for "peppiness" describe an atmosphere that is lacking in energy, liveliness, and excitement.