The word "birdbrained" is often used to describe someone who is foolish or lacking intelligence. However, there are many antonyms that can be used to portray the opposite of this term. Some of these antonyms include intelligent, smart, bright, astute, shrewd, wise, and insightful. These words describe individuals who possess a high level of cognitive abilities, critical thinking skills, and rationality. Using these opposite words instead of "birdbrained" can help to elevate the description of an individual and showcase their intelligence and cleverness rather than their supposed foolishness.