[Scott]

Hitting on the main question again, I was just reading the history of the black speech on Ardalambion a few moments ago and I found this:
"Where did the vocabulary of the Black Speech come from? Surely Sauron had no more "love of words or things" than his servants had, and one might well think that he simply invented words arbitrarily. This may be true in some cases, but it appears that he also picked words from many sources, even the Elvish languages: "The word uruk that occurs in the Black Speech, devised (it is said) by Sauron to serve as a lingua franca for his subjects, was probably borrowed by him from the Elvish tongues of earlier times" (WJ:390). Uruk may be similar to Quenya urco, orco or Sindarin orch, but it is identical to the ancient Elvish form *uruk (variants *urku, *uruku, whence Q urco, and *urkô, whence perhaps S orch). But how could Sauron know Primitive Quendian? Was he the one who took care of the Elves Morgoth captured at Cuiviénen, and perhaps even responsible for the "genetic engineering" that transformed them into Orcs? As a Maia, he would easily have interpreted their tongue (WJ:406). To the first Elves, Morgoth and his servants would be *urukî or "horrors", for the original meaning of the word was that vague and general, and Sauron may have delighted in telling the captured Elves that they were to become *urukî themselves. In his mind, the word evidently stuck.

But there were also other sources for Black Speech vocabulary. The word for "ring" was nazg, very similar to the final element in the Valarin word mâchananaškâd "the Doom-ring" (WJ:401, there somewhat differently spelt). Being a Maia, Sauron would know Valarin; it could indeed be his "mothertongue", to use the only term available. If it seems blasphemous to suggest that the tongue of the Gods may have been an ingredient in Sauron's Black Speech, "full of harsh and hideous sounds and vile words", it should be remembered that according to Pengolodh, "the effect of Valarin upon Elvish ears was not pleasing" (WJ:398). Morgoth, technically being a Vala, must have known Valarin (or at least picked it up during the ages he was captive in Valinor). According to LR:178 he taught it to his slaves in a "perverted" form. If so, Valarin naškâd "ring" may have produced nazg in one Orkish dialect of the Second Age, from which Sauron took it."(www.ardalmbion.com)
So I guess it has it's roots in Elvish and Valarin. That is of course if you rely wholeheartedly upon Ardalambion as a viable source of information. I myself do.

~Scott