The term 'co-aunt' defines two or more women who share the same nieces or nephews. However, there are a variety of synonyms used to describe this relationship. One of the most common terms is 'aunt-in-common' - a phrase that describes an aunt who is related to multiple siblings. Another synonym for 'co-aunt' is 'auntie-palooza,' reflecting a feeling of joy and excitement that arises when all the aunts are together. Some other synonyms for the term 'co-aunt' include 'shared aunt,' 'common aunt,' or 'joint aunt.' Ultimately, the use of any synonym depends on the individual and the relationship they have with their co-aunts.