Although Tolkien is praised for his obvious abilities with language and the cohesiveness to those fictitious languages in his work, there are still a few enigmas within these fictional tongues. One instance of this is the dwarven word for Celebdil, the Silver Point, the mountain on which Gandalf fought and defeated the Balrog. In Khuzdul, the dwarven language, it is called Zirakzigil.
In the mythology, as a rule, the dwarves teach their own language to no one; in fact, they do not even tell others their real names (i.e. Gimli has a dwarven name that wasn’t even ‘known’ to Tolkien). Therefore, there are many words used in Khuzdul that are a mystery in their meaning. In old notes by Tolkien he says that Zirakzigil means “silver spike,” and says the element “zirak-” means “silver” and “zigil-” means “spike.” However, in another place the exact opposite is written. We may never know which element means silver or spike.
Extra information on Zirakzigil:
Gandalf, after falling into the abyss in Khaza-dûm with the Balrog, finds the infamous, lost Endless Stair which goes, without break, from “the lowest dungeon to the high peak.” This “highest peak” happened to be Zirakzigil. The entrance to the peak was lost many lives ago and had not been used since. Here he fought with, and defeated, the Balrog. He also died there and was recovered by Gwaihir, the Lord of the Eagles.