"Most down in mouth" refers to a person who is extremely sad, unhappy, and depressed. The antonyms for this phrase could be: cheerful, happy, content, pleased, thrilled, and overjoyed. These words describe individuals who are in good spirits, optimistic about life, and generally feel good about themselves and their surroundings. When someone is cheerful or happy, they tend to have a positive outlook on life and can easily spread their joy to others. Similarly, when someone feels content or pleased, they have a sense of satisfaction and peace of mind. As for those who are thrilled or overjoyed, they feel intense emotions of excitement and happiness.