The word "un-fixes" means to undo or reverse the fixing of something. Its antonyms are words that represent the opposite meaning with "fix." These antonyms are "fix," "fasten," "secure," "attach," "anchor," and "stabilize." These words convey the action of firmly establishing or making something steadfast in its place. When we speak of fixing something, it means to make it firm or stable, while "un-fixes" mean to release or dismantle it. Therefore, the antonyms for "un-fixes" are essential in expressing the idea of assembling or setting something up in place.