Mammoth Uncensored Word List:
20 words ending with in, 14 letters long

andromedotoxin apolipoprotein corticotrophin cyanocobalamin erythropoeitin erythropoietin ferrimyoglobin haemagglutinin immunoglobulin mechanoprotein methaemoglobin oxyhaemoglobin petroporphyrin phosphocreatin phosphoprotein protoporphyrin streptothricin thromboplastin thrombopoietin thrombospondin