There are a total of 10 11-letter words containing 'quiet', and the number may vary in different dictionaries. You can specify the dictionary and order.

• disquieting ₂₅
• disquietude ₂₄
• inquietudes ₂₄
• quietnesses ₂₂
• unquietness ₂₄
• disquietens ₂₁
• disquietful ₂₄
• disquietive ₂₄
• disquietous ₂₁
• quietenings ₂₁

There are 10 11-letter words containing quiet in the well-known word game dictionary, 5 in the Scrabble US (US/Canada/Thailand - TWL/NWL) dictionary, and 10 in the Scrabble UK (International - SOWPODS/CSW) dictionary, and 5 in the Words with Friends (WWF) dictionary.