Halfwitted is a derogatory term used to describe someone who is mentally deficient or unintelligent. Antonyms, or opposite words, for halfwitted could include intelligent, bright, sharp, shrewd, astute, and clever. Someone who is intelligent is quick-witted, able to think critically and solve problems easily. Bright individuals possess a high level of intelligence and possess sharp minds. Shrewd individuals are clever and astute, capable of making good judgments and quick decisions. Clever individuals have innovative and witty ideas, providing solutions that may not be obvious. Therefore, using these words as antonyms for halfwitted suggests that the individual is intelligent, proficient, and sharp-minded.