This is the original text from a source* you want to use:
Woman, in the cult of True Womanhood presented by the women's magazines, gift annuals and religious literature of the nineteenth century, was the hostage in the home.
Below the student is plagiarizing. The reader has no way of knowing that the term "cult of True Womanhood" was first coined by someone else (Barbara Welter).
In this essay, I will use the cult of True Womanhood as a lens through which I will examine the life of poet Emily Dickinson.
If you fail to make it clear in the text that a term is not your own, you are committing plagiarism (even if you put in your bibliography a full citation to where the term came from, that still isn't enough).
* Welter, Barbara. "The Cult of True Womanhood: 1820-1860." American Quarterly, vol. 18, no. 2, 1966, pp. 51-174. JSTOR, www.jstor.org/stable/2711179.