Though all languages, including dwarvish – Khuzdul -, stem from Aule, the dwarvish language is alien to the other inhabitants of Arda. When the Eldar met the first Dwarves, they "could understand no word of the tongue of the Naugrim, which to their ears was cumbrous and unlovely" (SIL). Whereas Felagund had not too much trouble with understanding the language of the people of Beorn the Old.
Very little is known about the dwarvish tongue, and even less about dwarvish names.
The dwarves considered their language and specifically their names a secret. They were reluctant to teach their language to elves and men. And Appendix F to LOTR tells us: "Their own secret and 'inner' names, their true names, the Dwarves have never revealed to any one of alien race. Not even on their tombs do they inscribe them." So - for instance - even Balin's name given on his tomb is not his real dwarvish name, it is the name by which he wanted to be known to elves and men.
What we do know is this:
The dwarvish tongue is largely structured around consonants. In a way comparable to Arabic and Hebrew, the words are to be recognized by their consonants, vowels are only there to express subtle changes of meaning and context (for instance masc-fem, or past-present). In other words, dwarvish stems consist of consonants only. Quite often vocals can be left out altogether, which is why the language is so "guttural" and alien to others, 3 or 4 consonants in a row is no exception. We can safely assume that for purposes of writing down, vowels were written where they were assumed to be heard - more or less.
The essence of dwarvishness is given with the stem KH-Z-D. We find it in Khazad (dwarves), Khuzdul (dwarvish) and Nulukkhizdin (Nargothrond). This is a fine example of changing vowels around steady consonants. It has been suggested that the "real" meaning of KH-Z-D is seven (cf. Numenorean hazid/hazad).
Even the limited vocabulary we have of dwarvish words might well be a list of dwarvish adaptations from mannish. Tharkun – wizard – is so reminiscent of Zigurun (Numenorean for wizard). And this is precisely the problem: when we think we can understand a dwarvish word, is that because it is a dwarvish word related to known languages, or is it just a dwarvish use of those other languages?
The bad news about dwarvish – we hardly understand it -, might be good news about dwarvish names: For in most cases, names of dwarves are not dwarvish at all. They are just the names under which dwarves make themselves known in the world, and for this they use mannish and sometimes elvish words which they phonetically adapted if necessary.
Cf. Appendix F to LotR: "Gimli’s own name, however, and the names of all his kin, are of Northern (Mannish) origin".
Gimli is an adaptation from Gimil, the Numenorean adaptation from Sindarin Gil which means "star".
The names Durin, Fundin, Thorin and those of his 11 companions, all are adaptations. Mostly meaningless, sometimes meant to be funny or typical (BomburJ ), and incidentally meaningful.
But what about the name of that great Dwarvenlord of Belegost Azaghal, who wounded Glaurung? It certainly sounds truely dwarvish. To know what Azaghal means - if and as far as the name is dwarvish -, we would have to know the true meaning of Z-GH-L. And we do not, so we have to work the other way around, and look what we can learn from the complete spectre of Arda languages. What can we thus derive?
We have the Numeanorean phrase: "Ar-Pharazôn azaggara Avalôiyada", meaning Ar-P waged war against the Valar ( Unfinished Tales). This line of thinking is supported by the Sindarin stem for war: "Auth".
Thus Azaghal quite probably means "warrior".
But precisely because the dwarves were a secretive people, especially about their tongue and particularly about their names, we will never be certain about any dwarvish name.
This is perhaps best expressed by the name Thorin (is or is not related to Sind. "thurin": secret, hidden).
But the names of Thorin, Durin and Thrain
could give us a clue about the ‘hidden’ meaning of TH-R-N. Thus we
hidden word of the secret Khuzdul tongue, the hidden word for secret. Typical:)
the Ardalambion pages ( http://www.uib.no/people/hnohf )
J.R.R. Tolkien : Silmarillion, The Lord of the Rings, Book of Lost Tales 1 and 2, Unfinished Tales .