The definition of auntie is an affectionate term used for one of your parents' sisters or sisters in law.
An example of auntie is your favorite relative, your mom's sister.
aunt: a familiar or affectionate form
nounpl. aunt·ies Informal
- Diminutive of aunt
- Term of familiarity or respect applied to an elderly woman.
- Affectionate term used by a young person of an unrelated adult female family friend.