The word "shadowlike" describes something that resembles a shadow or is shadowy in nature. Its antonyms would be words that describe things that are bright, clear, or well-defined. Some possible antonyms for "shadowlike" might include words such as vivid, distinct, clear, sharp, bright, and radiant. Other possible antonyms might include words like resplendent, luminous, brilliant, sunny, and illuminated. All of these words describe things that are the opposite of shadowy or dim, and they can help to paint a picture of something that is visible, bright, and easy to see.