The opposite of "worthless" is "valuable." Something that is valuable has worth, use, or importance. It is something that is considered precious, significant or useful. Another antonym for "worthless" is "priceless." Priceless items are those whose worth cannot be measured in monetary terms. They are usually sentimental, irreplaceable or unique. Other antonyms for "worthless" include "significant," "worthy," "meaningful," and "useful." These words imply that the object or idea in question has importance, substance, or usefulness in some way. Overall, antonyms for "worthless" describe things that are the opposite of meaningless, irrelevant, or of no value.