'Sons-in-law' definitions:

Definition of 'Sons-in-law'

From: GCIDE

Son-in-law \Son"-in-law`\, n.; pl. Sons-in-law. The husband of one's daughter; a man in his relationship to his wife's parents. [1913 Webster]
To take me as for thy son in lawe. --Chaucer. [1913 Webster]