Sister-in-law

Full definition of sister-in-law

Noun

1. A female relative of one's generation, separated by one degree of marriage:
1. The sister of one's spouse.
2. The wife of one's sibling.
2. (less common) Co-sister-in-law: The wife of one's sibling-in-law.
1. The wife of the child of one's spouse.
2. The sister of the spouse of one's sibling.

Derived terms

• half sister-in-law
• co-sister-in-law

Related terms

• brother-in-law
• daughter-in-law
• father-in-law
• mother-in-law
• son-in-law

Usage notes

The plural sister-in-laws is occasionally seen, but this is considered incorrect by most sources; see, for example, http://www.wsu.edu/~brians/errors/sisterinlaws.html, despite being a common construction in American English.