eryth·ro·cru·o·rin \ ̷ ̷ˌ ̷ ̷ ̷ ̷ˈkrüərə̇, ru̇ə-\noun Etymology:erythr- + cruorin (old name for hemoglobin) : any of various red respiratory pigments that occur in blood, cells, or body fluids of several invertebrate animals and that are or are related to hemoglobins