Mammoth Uncensored Word List:
33 words ending with py, 12 letters long

aromatherapy bronchoscopy cerebroscopy chemotherapy crymotherapy curietherapy dactyloscopy dermatoscopy deuteroscopy ebullioscopy electroscopy enantiotropy galvanoscopy heliotherapy hydrotherapy hypermetropy hypnotherapy hysteroscopy laryngoscopy massotherapy neurotherapy ornithoscopy philanthropy phototherapy phytotherapy psilanthropy radiotherapy spectroscopy thoracoscopy tracheoscopy triggerhappy ureteroscopy urethroscopy