Untidy, meaning messy or disorganized, has several antonyms that convey the opposite meaning. The first antonym is tidy, which means neat and unkempt. A clean and organized living space is a good example. Another antonym is neat, which means clean and ordered. Speaking of clean, clean is another antonym of untidy that signifies things that are unmarked and well-maintained. Moreover, the word organized is another antonym that refers to the effective management of resources and actions to increase efficiency. There are many antonyms that can describe the opposite of untidy, and these are some of them.