The term "most unmilled" implies something that is very raw or unprocessed. Its antonyms would be words that indicate a high degree of refinement or processing. Some of the antonyms for "most unmilled" could be "highly processed," "polished," "refined," "finished," "milled," "processed," "clean," "smooth," or "purified." For example, a diamond that has been cut and polished to perfection would be the antithesis of "most unmilled." Similarly, a silk garment that has undergone extensive processing to achieve a lustrous finish would be another example of an antonym for "most unmilled.