There are a total of 50 9-letter words containing 'pto', and the number may vary in different dictionaries. You can specify the dictionary and order.

• acceptors ₁₈
• adaptogen ₁₆
• apoptosis ₁₅
• apoptotic ₁₈
• aptonymic ₂₁
• asymptote ₁₇
• captopril ₁₉
• corruptor ₁₆
• cryptogam ₂₂
• cryptonym ₂₃
• cryptozoa ₂₆
• deeptoned ₁₅
• disruptor ₁₄
• excerptor ₂₂
• inceptors ₁₆
• leptosome ₁₆
• leptotene ₁₄
• optometer ₁₅
• optometry ₁₇
• oviraptor ₁₆
• preceptor ₁₈
• preemptor ₁₈
• proptoses ₁₅
• proptosis ₁₅
• ptomaines ₁₆
• raptorial ₁₃
• receptors ₁₅
• sculptors ₁₇
• tiptoeing ₁₅
• uptossing ₁₆
• uptowners ₁₇
• apoptoses ₁₃
• leptophos ₁₆
• peptonize ₂₂
• ptomainic ₁₅
• receiptor ₁₃
• septorias ₁₁
• deceptory ₁₇
• exceptors ₂₀
• monoptote ₁₃
• optophone ₁₆
• peptonise ₁₃
• recaptors ₁₃
• scriptory ₁₆
• susceptor ₁₃
• symptoses ₁₆
• symptosis ₁₆
• symptotic ₁₈
• triptotes ₁₁
• tuptowing ₁₅

There are 50 9-letter words containing pto in the well-known word game dictionary, 34 in the Scrabble US (US/Canada/Thailand - TWL/NWL) dictionary, and 46 in the Scrabble UK (International - SOWPODS/CSW) dictionary, and 31 in the Words with Friends (WWF) dictionary.