Entry 1 sense Webster, 1913 Fuscin · Fus·cin · IPA /ˈfʌsɪn/ 01 n. A brown, nitrogenous pigment contained in the retinal epithelium; a variety of melanin. 1. A brown, nitrogenous pigment contained in the retinal epithelium; a variety of melanin.(Physiol. Chem.)