The word "most moldered" refers to something that is decaying or decomposing to a great extent. Its antonyms, or words with the opposite meaning, would be "fresh," "new," "vibrant," "pristine," and "unspoiled." These words describe things that are not deteriorated or decaying. For example, a fresh bouquet of flowers, a new car, or a pristine white dress are all antonyms for something that is most moldered. These words are important to use because they help to convey a completely different meaning and image for an object, person, or situation, making them useful when trying to describe something in detail.