She is a plain middle-aged woman who has had to work hard for everything.
"Think what it must be like for a plain young woman!"
To his surprise, he falls in love with this plain young woman.
She was a plain young woman, thick and dark with a worn face.
He hadn't been in love with her, of course, but though a plain woman she was quite a pleasant one.
She might in other circumstances have been quite a plain woman.
"Was she also a plain woman, and much older than the Colonel?"
She was a short woman, rather plain and chubby, just coming into middle age.
I looked at the clerk, a plain woman some years my senior.
She was a plain young woman wearing a white serving dress.