I am really skeptical about the idea that Orpah is derived from the word meaning "back of the neck." This seems like an after the fact "folk etymology" made up by medieval rabbis who were writing commentaries about the character that were frankly misogynist and derogatory. If Orpah was a real person, it makes no sense that her parents would have actually named her "back of the neck", and I don't think the author of the Book of Ruth would have given her a name that's insulting like that since the character really is not presented as a bad person in the story.