The term "most oldish" implies a state of age or antiquity. Antonyms for this term would include youthful, modern, contemporary, and new. These words represent the opposite of the concept of oldish and suggest a sense of newness, vitality, and freshness. Other antonyms that could be used to describe the opposite of oldish include futuristic, trending, innovative, and groundbreaking. When looking to contrast the idea of oldish, it is important to consider words that communicate a sense of modernity and youthfulness. This will help to create a clear distinction between the old and the new, the past and the present.