There are a total of 18 4-letter words containing 'by', and the number may vary in different dictionaries. You can specify the dictionary and order.

• abye ₉
• abys ₉
• baby ₁₂
• byes ₉
• byre ₉
• byrl ₁₀
• byte ₉
• doby ₁₀
• gaby ₁₁
• goby ₁₁
• inby ₁₀
• orby ₉
• ruby ₁₀
• toby ₉
• upby ₁₃
• byde ₁₀
• byke ₁₃
• moby ₁₁

There are 18 4-letter words containing by in the well-known word game dictionary, 15 in the Scrabble US (US/Canada/Thailand - TWL/NWL) dictionary, and 18 in the Scrabble UK (International - SOWPODS/CSW) dictionary, and 15 in the Words with Friends (WWF) dictionary.