Meaning of fan vault

fan' vault"

Pronunciation: [key]
  1. a vault composed of a number of concave conoidal surfaces, usually four, springing from the corners of the vaulting compartment and touching or intersecting at the top, often decorated with ribs. See illus. under.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.