The antonyms for the word "most fine-grained" include "coarse," "rough," "gritty," and "granular." Coarse refers to something that is rough in texture, while rough indicates an uneven and jagged surface. On the other hand, gritty suggests something that contains small particles or is sandy, and granular is used to describe materials that are made up of distinct grains or particles. These antonyms are helpful when trying to describe something with a different level of detail or texture than something that is most fine-grained.