Mammoth Uncensored Word List:
22 words ending with h, 16 letters long

bathythermograph chemoheterotroph chemoorganotroph chromolithograph decicentillionth lithoheterotroph microseismograph nonagintillionth novendecillionth octodecilliardth octogintillionth petrosomatoglyph phonocardiograph photochronograph photoheterotroph quindecilliardth quingentillionth sexagintillionth trecentilliardth trescentillionth trigintilliardth unvigintillionth