Mammoth Uncensored Word List:
32 - 16 letter words starting with he

headmistressship heavyheartedness hemagglutinating hemagglutination hemangioblastoma hemangiosarcomas hematoporphyrins hemiachromatopsy hemichromatopsia hemicorporectomy hemilaryngectomy hemipelvectomies hemoglobinopathy hemopneumothorax hemorrhoidectomy hendecasyllabics hendecasyllables hepatocarcinomas hepatolenticular hepatopancreases hepatopancreatic hepatotoxicities hermaphroditisms heterochromatins heterokaryosises heterotetrameral heterozygosities hexachlorethanes hexachloroethane hexachlorophenes hexapentagesimal hexylresorcinols