The term "belles-lettres" refers to literary works that are considered aesthetically pleasing, such as poetry or fiction. Antonyms for the word "belles-lettres" may include prosaic or mundane literature, such as technical or scientific writing. Other antonyms may include rough or coarse works, such as crass comedy or gritty realism. Belles-lettres may also connote a certain level of refinement or elegance, so antonyms could refer to works that are uncultured, unsophisticated, or poorly crafted. In any case, antonyms for belles-lettres would describe forms of expression that lack the beauty, grace, and artistry associated with the best works of literature.