"Rendered worthless" is an expression used to describe something that has lost all its value or worth. Antonyms, on the other hand, are words that are opposite in meaning to a particular word. Therefore, antonyms for the phrase "rendered worthless" could be "valued," "cherished," "beneficial," "profitable," "significant," and "important." For example, instead of saying "The old car has been rendered worthless," one could say "The antique car is highly valued," or "The vintage car is profitable." By using antonyms, we can convey a different tone and perspective, allowing us to communicate more effectively in different contexts.