Discussion Forum—A Way with Words, a fun radio show and podcast about language

Well whadaya know ... I think the "answer" (if we can call it that) might be same in both cases. I just checked the MW Unabridged (don't own OED) and the words "thaw" and "unthaw" are both there. Likewise "ravel" and "unravel."

No etymology about WHY both are needed, but they're in there. One respondent at Answers.com suggest that in cases like this, where the prefix "un" is added to a word that was already perfectly clear and well-defined, it's done to emphasize that "something which was already done (freezing or weaving) is now being undone." And as we all know, it's usage that ultimately drives the evolution of language. And that evolution is now always toward greater efficiency or concision.

"Boned" vs. "deboned" makes perfect sense to me. Again, no etymological info, but I suspect "deboned" came first and the shorter, more efficient "boned" came later. The meaning is clear to me, anyway, in either case.

No idea about "shelled" vs. "unshelled." "Deshelled" might actually be better. But to tell you the truth, I've never seen "unshelled" used to mean "nuts that have the shells removed." But then, I don't cook, so I rarely if ever encounter those terms. I do buy "salted in the shell" peanuts, and have occasionally grabbed the wrong bag labeled "unsalted in the shell." No confusion about those meanings.

Bottom line: It might not be pretty or efficient or concise, or even logical, but it's all been driven by usage. My best guess anyway.