Vault has several related meanings, all connected to the idea of something arched, secure, or requiring a leap:

1. A strong, secure room with thick walls and a heavy door, built to protect valuable things. Banks keep money in vaults. Museums store priceless artifacts in climate-controlled vaults. A vault's walls might be several feet thick, made of reinforced concrete and steel, designed to resist break-ins, fires, and explosions.
2. An arched roof or ceiling, like the kind you see in old cathedrals. These vaulted ceilings curve gracefully overhead, creating a sense of spaciousness and grandeur. The Romans pioneered vault construction, using the arch shape to support enormous weight without interior columns.
3. To jump or leap over something, especially using your hands or a pole for support. Gymnasts vault over special equipment called a vaulting table. In track and field, athletes use a long flexible pole to pole vault over a high bar, sometimes clearing heights over 20 feet. When you place both hands on a fence and swing your legs over, you're vaulting it.

Whether describing a secured room, a curved ceiling, or an athletic leap, vault suggests something impressive, either in strength or in the skill required to achieve it.