The word "curvity" is not a commonly used word in the English language, and therefore, there are no specific antonyms for it. However, if we consider the meaning of the word, which refers to a curved or rounded form, we can derive some opposite terms. The antonyms may include words such as straightness, flatness, linearity, or angularity. These are the terms that describe sharp angles, edges, and straight surfaces, which are the opposite of curves and rounded shapes. Overall, while there are no exact antonyms for the word "curvity," we can use these contrasting terms to form the opposite meaning.