The word unnoteful means not useful or lacking in usefulness. The antonyms for unnoteful are words that denote full of usefulness, advantageous, helpful or valuable. Some antonyms for unnoteful include useful, beneficial, valuable, effective, gainful, advantageous, productive, profitable, fruitful, and plausible. These words are used to describe something that enhances the quality or usefulness of a situation, activity, or object. When used in context, the antonyms bring out the positive connotation of a sentence and can help to convey a message that is optimistic, progressive, and beneficial.