1. A sons wife.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• saughter-in-law,
• xaughter-in-law,
• caughter-in-law,
• faughter-in-law,
• raughter-in-law,
• eaughter-in-law,
• dzughter-in-law,
• dsughter-in-law,
• dwughter-in-law,
• dqughter-in-law,
• dayghter-in-law,
• dahghter-in-law,
• dajghter-in-law,
• daighter-in-law,
• da8ghter-in-law,
• da7ghter-in-law,
• daufhter-in-law,
• dauvhter-in-law,
• daubhter-in-law,
• dauhhter-in-law

The adjective form of the word "daughter-in-law" is "maternal".