The word "thick-witted" refers to someone who is slow to grasp things and not very intelligent. Some antonyms for this word include "clever," "smart," "intelligent," "astute," "sharp," "quick-witted," "brainy," "perceptive," and "bright." These words describe people who are quick to understand things, make logical decisions, and exhibit critical thinking skills. Someone who exhibits these traits is seen as intelligent and may be able to problem-solve quickly and efficiently. Using these antonyms in place of "thick-witted" can provide a more positive and accurate description of someone's abilities and mental capabilities.