hematoidin(n = noun.substance) bilirubin, haematoidin - an orange-yellow pigment in the bile that forms as a product of hemoglobin; excess amounts in the blood produce the yellow appearance observed in jaundice;
A crystalline or amorphous pigment, free from iron, formed from hematin in old blood stains, and in old hemorrhages in the body. It resembles bilirubin. When present in the corpora lutea it is called hæmolutein. [1913 Webster]