Undiffused means something that is not well spread or widespread. Therefore, antonyms for undiffused would include words that indicate the opposite, that is, something that is widely spread or prevalent. Some antonyms for the word "Most Undiffused" could be words like common, prevalent, widespread, dominant, extensive, abundant, prevalent, profuse, popular, and general. These words indicate that something is largely present and well-spread in a particular area or context. Using antonyms for "Most undiffused" can help convey the opposite meaning of something being widespread and well-spread, rather than being limited or confined.