A familiar, affectionate term for one's grandmother (the family's grandmother). Often used by grandchildren or children; usually written in kana.
毎週日曜日におばあちゃんの家で昼ご飯を食べる。
Every Sunday I eat lunch at my grandmother's house.
遠くに住んでいるおばあちゃんに手紙を書いた。
I wrote a letter to my grandmother, who lives far away.
「おばあちゃん、明日来るよ」と子どもが言った。
The child said, 'Grandma, I'll come tomorrow.'
A familiar way to refer to an older woman or elderly lady (not necessarily a relative). Depending on context it can sound casual or overly familiar.
駅前でおばあちゃんが野菜を売っていた。
An old woman was selling vegetables in front of the station.
あそこのおばあちゃんはいつも親切に話しかけてくれる。
The elderly woman over there always speaks kindly to people.