sister-in-law
UK: ˈsɪstər ɪn lɔː | US: ˈsɪstər ɪn lɔː
n. the wife of one’s brother
n. the sister of one’s spouse
n. the wife of one’s sibling (gender-neutral usage)
The term "sister-in-law" combines "sister" (Old English sweostor, meaning a female sibling) with the prepositional phrase "in law," which historically denoted relationships formed through marriage rather than blood. The "in law" component reflects medieval legal terminology, where marital ties were considered binding under canon and civil law. Over time, the phrase evolved into a compound noun, simplifying the description of extended familial relationships.
My sister-in-law hosted a dinner party for the family.
She gets along well with her brother’s wife, her sister-in-law.
His sister-in-law helped him plan the surprise birthday party.
In some cultures, the term "sister-in-law" includes cousins by marriage.
They celebrated the holiday with their siblings and sisters-in-law.