The word "in-festive" is not commonly used in everyday conversations or writing. However, if we break down the word, we can come up with some possible antonyms. The prefix "in-" typically means "not" or "lacking," while "festive" refers to something that is joyous and celebratory. Therefore, the antonyms for "in-festive" could include festive, merry, joyful, lively, colorful, happy, cheerful, and vibrant. These words describe a lively and fun atmosphere, which is the opposite of what "in-festive" would denote. Overall, it is important to use context clues to determine the intended meaning of a word and its antonyms.