Miss Sneyd[1] is a character mentioned in Mansfield Park. She never appears in the book.
Miss Sneyd and her sister, Miss Augusta, are mentioned when Mary Crawford asks about whether or not Fanny Price is out in society or not. Tom Bertram talks about how he got in trouble with Miss Sneyd when he talked to the young lady's sister—who was not yet out—instead of her. Miss Sneyd considered this to be a major faux pas[2].