The antonyms for the word "art useful" would be "unskilled," "ineffective," or "unhelpful." These terms describe something that lacks usefulness or practical function. For example, an unskilled artist may produce artwork that is aesthetically pleasing but lacks practical application. Similarly, an ineffective tool or product may be deemed unhelpful due to its inability to fulfill its intended purpose. In contrast to "art useful," which denotes a skillful and productive creation, these antonyms connote something lacking in value or practicality. However, it is important to note that the value of art is subjective, and what may be considered unskilled or ineffective to one person may be meaningful and useful to another.