The word "most overrun" means something that has been taken over or occupied in great numbers. Antonyms for this word would be terms that describe places or situations that are not taken over, overrun or crowded. Some examples of antonyms for most overrun could be deserted, peaceful, uncrowded, calm or unoccupied. For instance, if we say that a place is deserted, it implies that there are no people or activities around, and it's not overrun by anything. Similarly, if we call a place peaceful or calm, it implies that it is free from chaos, disturbance or any form of overrun. Overall, antonyms for the word "most overrun" describe places that are serene, tranquil, and peaceful.