The word "un-mixed" denotes something that is pure, homogeneous or undiluted. Its antonyms are the opposite of these qualities. For example, mixed, adulterated, and impure are some of the antonyms for un-mixed. When something is mixed, it contains different components that are blended together, and it is no longer pure. Adulterated means that a substance has been contaminated or tainted. And impure refers to something that is not clean, clear, or true to its original form. In short, the antonyms of "un-mixed" are all associated with the lack of purity, homogeneity, and uniformity.