The opposite of "coined a phrase" would be "forgot a phrase" or "failed to come up with a phrase." "Abandoned a phrase" or "discarded a phrase" can also be used as antonyms for "coined a phrase." In other words, if someone is unable to think of a witty or catchy phrase to express their thoughts, they would not have coined a phrase. Similarly, if someone is unable to remember a particular phrase or saying, they cannot be said to have coined that phrase. Sometimes, people may struggle to find the right words, and in such cases, they could not have coined the phrase.