There are a total of 17 3-letter words containing 'os', and the number may vary in different dictionaries. You can specify the dictionary and order.

• bos ₆
• cos ₆
• dos ₄
• hos ₅
• kos ₇
• mos ₆
• nos ₄
• oos ₃
• ose ₃
• pos ₆
• sos ₃
• wos ₆
• gos ₄
• ios ₃
• los ₃
• yos ₆
• zos ₁₂

There are 17 3-letter words containing "os" in the well-known word game dictionary, 12 in the Scrabble US (US/Canada/Thailand - TWL/NWL) dictionary, and 17 in the Scrabble UK (International - SOWPODS/CSW) dictionary, and 12 in the Words with Friends (WWF) dictionary.