1A polite/respectful way to refer to one's mother (or someone else's), commonly used in conversation.
お母さん、今日の夕飯は何にする？
Mom, what should we have for dinner today?
お母さんはいつも優しくて、頼りになる存在だ。
My mother is always kind and reliable.
週末はお母さんと買い物に行った。
I went shopping with my mother on the weekend.
お母さんの誕生日には家族みんなでケーキを作った。
For Mom's birthday, the whole family made a cake together.
2Also used by a husband to address or refer to his own wife, as an extension of the parental address term.
結婚してから、彼は妻のことを名前ではなく「お母さん」と呼ぶようになった。
Since getting married, he started calling his wife "Mom" instead of using her name.
近所のご主人は、奥さんのことをいつも「お母さん」と呼んでいる。
The husband next door always calls his wife "Mom."
3In familiar or colloquial speech, used to address or refer to an older woman, similar to "you" or "she" — a dialectal, less common usage.
お母さん、そこの荷物落ちてますよ。
Excuse me, ma'am, you dropped something over there.
あそこにいるお母さん、毎朝ここを散歩してるんだよ。
That old woman over there walks here every morning.