bilirubin
n. an orange-yellow bile pigment produced from breakdown products of the hemoglobin of red blood cells. Bilirubin is excreted in bile, feces, and urine. An excess of bilirubin is often a sign of a liver disorder (or, in babies, liver immaturity or incompatibility with the mother’s blood group) and may cause deposits of yellowish pigments in the skin and other tissues, a condition known as jaundice. See also hepatitis.