"Peabrained" is a colloquial term that is used to describe someone who is foolish or stupid. Given that it is not a polite or respectful way of referring to someone, it is often better to use synonyms that are more formal. Some words that can be used instead of "peabrained" include uninformed, simple-minded, naive, inexperienced, and unintelligent. Each of these words reflects a lack of knowledge or awareness that can lead to poor judgment, bad decisions, or flawed reasoning. While it is important to be respectful and considerate of others, using appropriate language can also help to communicate more clearly and effectively.