As various forms of nonmonogamy have grown in social visibility, the subject has received academic treatment across a range of literatures, including philosophy. To aid in philosophical treatment, the paper addresses the narrow but fundamental topic of the meaning of nonmonogamy. By engaging with recent literature, it examines nonmonogamy as the rejection of or opposition to monogamy. After exploring the nature of opposition in this case, the paper develops the beginnings of a more detailed theory of nonmonogamy. How do monogamy (...) and nonmonogamy relate? If nonmonogamy is a rejection, what content does the concept of nonmonogamy have? The paper does not criticize monogamy or defend nonmonogamy, but it aims to take part in building the conceptual foundations for nonmonogamy as a political project. (shrink)