Mammoth Uncensored Word List:
18 - 17 letter words starting with pe

pedestrianisation pedestrianization pentachlorophenol pentanonagesimals pentasexagesimals pentylenetetrazol perchloroethylene perfunctorinesses pericardiectomies pericardiophrenic pericardiorrhaphy perimesencephalic permissiblenesses persnicketinesses perspicaciousness perspicuousnesses pestiferousnesses petrosomatoglyphs