- Sister-in-law is a woman who marries your brother or is your husband's sister.
An example of sister in law is the sister of your brother.
sister-in-law definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
noun pl. sisters-in-law
- the sister of one's husband or wife
- the wife of one's brother
- the wife of the brother of one's husband or wife
sister-in-law definition by American Heritage Dictionary
noun pl. sis·ters-in-law
- The sister of one's spouse.
- The wife of one's brother.
- The wife of the brother of one's spouse.