Nimble-witted is a term used to describe someone who is quick-witted, clever, intelligent, and mentally agile. The antonyms of nimble-witted are words that describe someone who is slow-witted, dull, stupid, or unintelligent. The antonyms of nimble-witted include dim-witted, dim, slow, obtuse, dense, and unintelligent. These words refer to someone who lacks the ability to think quickly or solve problems effectively. A person who is dim-witted may struggle to understand complex concepts or think critically. The opposite of nimble-witted, these words describe a person who is not quick on the uptake and is easily confused.