Among themselves, Dwarves spoke Khuzdul, a cloistered tongue known to virtually no one but themselves. Khuzdul changed little with time, being a sacred, spoken language of lore and not a cradle-speech. This "inner language" was well suited to the throaty Dwarven voice, since it had a deep tonal quality. Khuzdul was marked by harsh consonants and used two or three-consonant patterns to denote common concepts. For example, "K(h)-Z-D" structures refer to word roots equivalent that describe Dwarves or things essential to the Dwarven identity (e.g. "Khazad" — "Dwarves"; "Khazad" = "Dwarf; "Khuzdul" = Dwarvish").