Noncomplementary refers to things that don't match or are incompatible with each other. This word has a negative connotation, indicating a lack of harmony or congruency. Opposite or antonyms for noncomplementary include "matching," "compatible," "harmonious," "complementary," "congruent," "corresponding," "synergistic," and "attuned." These words describe things that work well together, complementing each other's strengths, and creating a positive outcome. For instance, in a relationship, compatible partners can enjoy each other's company and create a thriving partnership. In design, complementary colors can make an artwork more attractive, eye-catching, and diversified compared to noncomplementary colors.