Antonyms for the word "most all purpose" can vary depending on the interpretation of the term. If "most all purpose" means something that is versatile and can be used for various tasks, then antonyms can include specific, specialized, limited, and one-dimensional. However, if "most all purpose" means something that is not effective for any particular task, then antonyms can include functional, useful, efficient, and effective. In any case, it is important to understand the context of the term to properly identify its antonyms.