The sister or sister-in-law of one’s parent.
"My aunt Sarah came to visit her brother and his wife last weekend."
In plain English: An aunt is your mother's sister, father's sister, or either of their sisters' husbands who are married into the family.
"I stayed with my aunt at her house over the weekend."
Usage: Use aunt to refer specifically to your mother's, father's, step-parent's, or adoptive parents' sisters and their spouses. This term does not apply to the siblings of other relatives unless they are also a sibling to one of your own parents.
The word "aunt" comes from Old French ante, meaning "father's sister." It replaced the native English word modrie, which originally referred specifically to a maternal aunt.