The antonyms for the word "oral characters" can be the written language, silent or non-verbal communication, and visual representations. While oral characters primarily refer to the use of spoken words to convey ideas, the use of written language entails communicating through written or printed characters. Silent or non-verbal communication, on the other hand, pertains to conveying messages through gestures, facial expressions, and body language. Lastly, visual representations can be in the form of images, illustrations, and diagrams, which help in portraying ideas, concepts, and information. All of these antonyms can serve as alternative means of communication, depending on the context and purpose for which they are being used.