Zirakzigil was the Dwarves' name for one of the great peaks of the Misty Mountains, Celebdil (Silvertine), which located above the Dwarf kingdom of Khazad-dûm. (The other two peaks were Caradhras and Fanuidhol.) At its peak stood Durin's Tower, upon which the final battle between Gandalf and Durin's Bane (the Balrog of Moria) took place.
The Sindarin word for Zirakzigil is Celebdil
Celebdil is derived from celeb ("silver") and til (modified to -dil) ("horn," "point")
Therefore, Zirakzigil can be literally translated to "Silver Spike"