Thickwitted is a negative descriptor that refers to someone who is dull or slow-witted. Antonyms for this word would be intelligent, bright, sharp, clever or quick-witted. Someone who is described as thickwitted may struggle with grasping concepts, understanding ideas, or responding quickly to questions. The antonyms of thickwitted, however, denote a person with the opposite characteristics. They are individuals who are intellectual, perceptive, and sharp-minded, with the ability to think clearly and quickly. While thickwitted is a derogatory term, its antonyms portray a positive and high-achieving individual who is capable and competent.