The word "un-earthliest" is not a commonly used term. However, if we break it down, "un" is a prefix meaning "not," while "earthliest" means "most earthly." Therefore, antonyms for "un-earthliest" would be words that mean "most earthly" or "most down-to-earth." Some possible options could include extravagant, fanciful, dreamlike, or surreal. These words all imply a departure from reality and the mundane, suggesting a preference for the fantastic or imaginative. In contrast, words like practical, realistic, pragmatic, or sensible would represent a more grounded approach to life, which could be seen as an antonym for the term "un-earthliest.