fan vault(redirected from fan groin)
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A rib vault in which slender curving ribs radiate upward from the top of a column like the ribs of a fan to form inverted half cones. Common in late English Gothic architecture, fan vaults are often decorated with intricate tracery or paneling.
a vault composed of a number of concave conoid surfaces touching or intersecting at the top, with curved fanlike ribs radiating from the spring.