A sister-in-law (plural sisters-in-law) is the sister of one's spouse, the wife of one's sibling, or sometimes the wife of one's spouse's
Kaynak: Sister-in-law

His wife, Carolyn Bessette , and sister-in-law, Lauren Bessette, were also killed. The flight had departed from Essex County Airport (CDW
Kaynak: John F. Kennedy, Jr. plane crash

An aunt is a person who is the sister or sister-in-law of a parent. grand-aunt or great aunt) is the sister or sister-in-law of a grandparent.
Kaynak: Aunt