a (middle-aged or older) woman; used to address or refer to an older woman—often appears with suffixes like -san or -sama (e.g., 'oba-san').
駅でおばさんに道を聞かれた。
An older woman asked me for directions at the station.
あの人は田中さんのおばだと聞いた。
I heard that person is Mr. Tanaka's aunt.
すみません、おばさん、そこに座ってもいいですか？
Excuse me, ma'am, may I sit there?
子どものころ、近所のおばにお菓子をもらった。
When I was a child, a neighborly older woman gave me sweets.