There are a total of 33 7-letter words containing 'iou', and the number may vary in different dictionaries. You can specify the dictionary and order.

• anxious ₁₆
• bilious ₁₂
• carious ₁₁
• copious ₁₄
• curious ₁₂
• devious ₁₃
• dubious ₁₃
• ebrious ₁₁
• envious ₁₃
• folious ₁₂
• furious ₁₂
• haviour ₁₄
• impious ₁₄
• nimious ₁₂
• noxious ₁₆
• obvious ₁₅
• osmious ₁₁
• paviour ₁₅
• piously ₁₄
• rubious ₁₂
• sanious ₉
• saviour ₁₂
• serious ₈
• simious ₁₁
• tedious ₉
• various ₁₂
• vicious ₁₅
• badious ₁₀
• binious ₉
• bivious ₁₂
• cesious ₉
• corious ₉
• invious ₁₀

There are 33 7-letter words containing iou in the well-known word game dictionary, 26 in the Scrabble US (US/Canada/Thailand - TWL/NWL) dictionary, and 32 in the Scrabble UK (International - SOWPODS/CSW) dictionary, and 27 in the Words with Friends (WWF) dictionary.