Chef d'oeuvre is a French term that is commonly used in English to describe a masterpiece or a work of outstanding skill or artistry. It is a positive term that suggests excellence and greatness. Therefore, its antonyms are words that express the opposite meaning. Some of the antonyms for chef d'oeuvre include "disaster," "failure," "mess," "wreck," "junk," "trash," "garbage," and "abomination." These words suggest a lack of skill, talent, or visionary capacity. They describe things that are poorly crafted, unimpressive, or downright repulsive. Although these antonyms may not be pleasant to hear, they provide a useful contrast to the elevated stature of a chef d'oeuvre.