Warped web of a Gothic vault framed by a diagonal rib and stilted wall-rib, occurring when the wall-ribs are sprung from a higher level than the diagonal ribs, as when accommodating clerestory lights. As the web is distorted, twisted like a ploughshare, it is also called a plowshare vault. (Curl & Wilson, 2016)
Synonyms:
plowshare twist