The word for aunt in Italian is zia (feminine, plural: zie).
It comes from the Latin word thia and, as in English, is used to describe the sister of one’s mother or father, or the wife of one’s uncle (zio). To describe the latter, the term zia acquisita (aunt by marriage) is often used.
Mia zia abita in Italia da dieci anni.
My aunt has lived in Italy for ten years.
Prozia is the word for great-aunt, or the aunt of one of your parents.
Amongst the younger generation, the terms zio and zia are often used colloquially to say bro / sister (friend). It is used in particular in the expression bella zio or bella zia (lit: nice uncle or nice aunt) as a way of saying that you agree with something your friend has said or done. It is often followed by a friendly gesture such as touching one’s fist. It originated in the suburbs of Milan.
Ci vediamo alle 10 per una birra? – Bella zia, a dopo!
Are we meeting for a beer at 10? – Sure sister, see you later!
In some regions such as Bologna, zia has become an ironic nickname for a woman who behaves in a slow, awkward or clumsy manner, and may be used teasingly if, for example, she drifts off during a discussion or falls asleep during an evening out with friends.