He said she had undermined her strength…… " In the silence that fell, Scarlett saw her mother as she must have been in those last days, a thin power of strength in Tara, nursing, working, doing without sleep and food that the others might rest and eat.
There are no more uses of "undermine" in the book.
Show samples from other sources
Her father had a way of undermining his sister’s lectures on the innate superiority of any given Finch: he always told his daughter the rest of it, quietly and solemnly, but Jean Louise sometimes thought she detected an unmistakably profane glint in Atticus Finch’s eyes, or was it merely the light hitting his glasses?
Harper Lee -- Go Set a Watchman
He cocked his head, trying on his "I’m so wholesome" routine, but his bloodshot eyes undermined his efforts.