'Crusader' definitions:

Definition of 'crusader'

From: WordNet
noun
A disputant who advocates reform [syn: reformer, reformist, crusader, social reformer, meliorist]
noun
A warrior who engages in a holy war; "the Crusaders tried to recapture the Holy Land from the Muslims"

Definition of 'Crusader'

From: GCIDE
  • Crusader \Cru*sad"er\ (-s?"d?r), n. One engaged in a crusade; as, the crusaders of the Middle Ages. [1913 Webster]
  • Azure-eyed and golden-haired, Forth the young crusaders fared. --Longfellow. [1913 Webster]