The antonyms of the phrase "making firm" are "loosening," "weakening," "relaxing," "slackening," "softening," and "weakening." When we speak of making something firm, we refer to creating stability, strength, and security. The opposite is the loosening, which involves making something less tight, secure, and stable. When you relax your grip, your hold on something slackens. A modern language trend is to use opposite phraseology, such as "unmaking firm" or "de-firming." It's important to use an accurate antonym to avoid confusion and maintain clarity in communication. Knowing a word's antonyms can expand one's vocabulary and improve written and oral communications.