There are several synonyms for the obscure word "plumbean," which means to act in a foolish or silly manner. Some alternatives include clownish, buffoonish, goofy, foolish, and zany. Each of these words describes a person who behaves in a way that is entertaining or humorous, but also somewhat ridiculous. Other possible synonyms for plumbean might include imprudent, impractical, ridiculous, or irrational. Regardless of the specific synonym used, the concept of acting in a foolish or silly manner is one that is relatable to many people, and is often used in comedy and entertainment to bring joy and laughter to audiences.