The word "more pithless" means having less substance or significance. Some antonyms for this phrase include "substantial", "meaningful", "purposeful", "thoughtful", "substantive" and "significant". These words suggest an opposite meaning of something that has depth, purpose, and value. When used in a sentence, these antonyms can help create a contrast that highlights the importance of an idea or object. For example, "While her first novel was more pithless, her second one was substantial and thought-provoking." Overall, using antonyms can be helpful in conveying a deeper meaning and emphasizing the significance of something.