The antonyms for the phrase "is down the mouth" include words like cheerful, content, happy, satisfied, and pleased. When someone is not "down the mouth," they are generally in good spirits and have a positive attitude towards life. These opposite terms can be used to describe people who are optimistic, hopeful, and joyful about their circumstances.
If someone is feeling "down the mouth," they might be described as sad, depressed, or pessimistic. In this case, it's important to use antonyms that convey a brighter outlook and a happier disposition.
Antonyms can be useful in helping people to express themselves more accurately and precisely. By understanding the opposite meanings of a word or phrase, we can communicate our thoughts and feelings more effectively.