The word "makes impure" refers to something that detracts from the purity, cleanliness, or quality of something else. Some antonyms of "makes impure" might include "purifies," "cleanses," "clarifies," "sanitizes," or "refines." These terms suggest the opposite action, making something cleaner, clearer, or more refined than it was before. Other antonyms might include "improves," "enhances," "polishes," "beautifies," or "upgrades," as these words imply a positive transformation or addition rather than a negative one. Ultimately, the choice of antonym depends on the context and the connotations that the speaker or writer wishes to convey.