Mammoth Uncensored Word List:
21 words ending with hs, 17 letters long

bathythermographs chemoheterotrophs chemoorganotrophs chromolithographs decicentillionths lithoheterotrophs microseismographs nonagintillionths novendecillionths octodecilliardths octogintillionths petrosomatoglyphs phonocardiographs photoheterotrophs quindecilliardths quingentillionths sexagintillionths trecentilliardths trescentillionths trigintilliardths unvigintillionths