Many moon is a term that refers to a long, unspecified amount of time. The antonyms of this phrase would be words that signify a lesser amount of time or a brief duration. These can include terms like "moment," "instant," and "jiffy," which all indicate a very short period. Other antonyms could be words like "few," "scant," or "limited," which refer to a small number or amount of something. Alternatively, antonyms could be words that emphasize the precise measurement of time, such as "minute," "second," and "hour," which all convey a specific and defined amount of time.