From Longman Dictionary of Contemporary Englishmaiden auntˌmaiden ˈaunt noun [countable] old-fashioned SSFan aunt who has never married
Examples from the Corpus
maiden aunt• When he was eighteen months old, the family broke up, his care passing to a maiden aunt.• Your aupair may be a born maiden aunt.• The man of letters and the maiden aunt.• The maiden aunt who was invited to Walsingham House arrived in a four-wheeler. 