The word "most cottony" refers to something that is extremely soft, fluffy, and lightweight, like a cloud or a cotton ball. The antonyms for this word would be something that is hard, rough, and heavy, such as a rock or a brick. Another possible antonym would be something that is slick and smooth, like a polished surface or a slippery slope. These words are the opposite of "most cottony" because they have a completely different texture and feel. While "most cottony" invokes a sense of comfort and warmth, the antonyms suggest a sense of hardness or friction.