The Meaning of the Phrase ‘In-Law’

The phrase ‘in-law’ had a different meaning prior to the mid-19^th century than it has today. In the 1851 census, for example, the term son- or daughter-in-law could mean ‘step-son’ or ‘step-daughter’, ie children of the wife of the head of the household by a previous marriage.

In Dickens’s Pickwick Papers Sam Weller addresses his step-mother as ‘mother-in-law’.