I just read the introduction to William Dean Howell’s Indian summer; I usually read introductions after I’ve read the book.
In the introduction, by Wendy Lesser, she wrote, “Let me say a brief word about the title. Unlike comparable nineteenth-century terms such as “redskins” and “Indian giving,” the phrase “Indian summer” has not yet been banned from polite conversation. Its etiology is uncertain, and the claims to what is particularly “Indian” about this late-fall phenomenon range from the redness of the autumn leaves to the ceremonial beliefs and planting habits of the country’s original inhabitants.”
I would think that the more accurate word should be, “etymology” because she’s referring to the title of the book and specifically the usage of that phrase. Etiology meaning, “the cause, set of causes, or manner of causation of a disease or condition; a branch of knowledge concerned with causes,” is obviously not the appropriate word. The etymology of the phrase, Indian summer, is what is uncertain, not the causation of the unseasonal weather occurrence.
Perhaps I’m being too punctilious? The publication of the book is from The New York Review of Books, but apparently none of their proofreaders or copy editors detected the erratum.
Bold emphasis added