Mammoth Uncensored Word List:
12 words ending with hs, 18 letters long

duovigintillionths lymphoscintigraphs nonagintilliardths novendecilliardths octingentillionths octogintilliardths quingentilliardths septendecillionths sesvigintillionths sexagintilliardths spectroheliographs untrigintillionths