As you know, Thomas Hardy considered Tess in Tess of the D'Urbervilles a pure woman since the subtitle of the work is "A Pure Woman." I have not taught or researched the novel, so you may get a far more detailed answer from another editor, but I can give you the obvious meaning of Hardy's subtitle.
Tess suffers throughout her life for, in the eyes of society, being impure. She is used and abused by society in general and men in particular. With his subtitle, along with the text of the novel, of course, Hardy is suggesting that there is far more to being pure, to being a decent human being, to being a loving person, than just whether or not someone has had sex out of wedlock. Hardy is commenting on prudish, hypocritical Victorian values. Tess is pure, Hardy seems to be suggesting, because of her personality and her character, etc., regardless of what society thinks of her.
She is certainly a better human being than any of the men who abuse her and judge her.
There is, therefore, of course, as you've probably concluded, an element of irony in Hardy's subtitle.
I believe that Tess is an extremely pure and victimized woman. In the book "Tess of D'Ubervilles" Tess begins her life as a sweet girl who trusts men. She is beautiful and innocent and she does not really associate her beauty to the sexual desire that men have for her. Tess is trapped and victimized by the men in her life. She has become the sexual toy and not much more. She has little money, no education, and not much to help her to alter her course in life. When she finally makes her fatal decision, she has already felt her life was a death sentence.
Society and the ability of the men to manipulate her innocence is what was not pure, not Tess.
well i have read and analysed the novel and my point of view is that.... tess is as we know is an innocent girl although she was educated bt not experienced..she does not know how to live carefully in this lustfull world of men.....now the real point is of "purity" which comes from soul not from body and she was pure and innocent from the inner part of her soul..secondly Hardy also shows that a bad deed done intentionaly is sin but here tess was raped so she had no intention of any sexual intercourse thats why she is pure before hardy...