Ringent, meaning "open-mouthed or gaping," is a relatively uncommon word. Some potential antonyms for this word would include "closed" or "shut." These words are more commonly used and can help to provide a better understanding of the opposite meaning of ringent. Another potential antonym could be "composed" or "calm," as ringent often connotes a sense of excitement or even aggression. However, it's important to note that there isn't a perfect or definite antonym for every word, and the opposite meaning of a word may vary based on the context in which it's used.