Mammoth Uncensored Word List:
34 words ending with h, 15 letters long

astrophotograph bluestockingish chemolithotroph chromoxylograph ducentilliardth duocentillionth duodecilliardth echocardiograph electromyograph ergatandromorph hyetometrograph macrophotograph microphonograph microphotograph microradiograph multiwavelength nongentillionth octodecillionth photoheliograph photolithograph photomacrograph photomicrograph photozincograph rechromatograph schoolmasterish sescentillionth thermobarograph threepenceworth threepennyworth trainspotterish trecentillionth tredecilliardth trigintillionth vigintilliardth