Siege Perilous
noun Arthurian Romance.
a vacant seat at the Round Table that could be filled only by the predestined finder of the Holy Grail and was fatal to pretenders.
British Dictionary definitions for siege perilous
Siege Perilous
noun
(in Arthurian legend) the seat at the Round Table that could be filled only by the knight destined to find the Holy Grail and that was fatal to anyone else
Word Origin for Siege Perilous
from
siege (in the archaic sense: a seat or throne)