"Art firm" is a term that refers to a company or business involved in the creation and sale of artworks. However, if we are to look for antonyms for this word, we might consider words that connote a lack of artistry or creativity. Words such as "mundane," "prosaic," or "unimaginative" would serve as fitting antonyms for "art firm." In other words, these words describe entities that are far removed from art or the creative process. These antonyms suggest an absence of originality, inspiration, and aesthetic value, which are qualities that define a true "art firm." Therefore, these words might be used to describe businesses that focus solely on profit rather than artistry.