The plural of son-in-law is sons-in-law.
A son-in-law is the husband of one's daughter. It refers to the familial relationship between a man and his spouse's parents. Son-in-law is a term commonly used in various cultures to describe the legal or social connection formed through marriage.
Singular form of "son-in-law":
Plural form of "son-in-law" (sons-in-law):