Muttonheaded is a term that describes someone who is foolish or has a lack of intelligence. Some synonyms for this word include dim-witted, brainless, idiotic, senseless, and witless. Other similar terms include foolish, inane, dumb, and irrational. Each of these words describes someone who may not have the ability to think logically or make good decisions. While there may be different levels of intelligence depending on the person, these synonyms all describe someone who is lacking in common sense and basic understanding. It is important to be aware of these synonyms to effectively communicate with others and properly convey intended meanings.