a person who makes a long and determined effort to achieve something that they believe to be right or to stop something they believe to be wrong十字军战士；（某）运动的参加者synonymcampaigner
She was a moral crusader who campaigned on a range of issues.她过去在一系列问题上大力倡导道德。
crusader for somethingHe has set himself up as a crusader for higher standards in the media.他已经成为媒体更高标准的十字军。
often Crusader
a fighter in the Crusades in the Middle Ages十字军战士；（某）运动的参加者
In 1204 Crusaders captured Constantinople.在1204年，十字军占领了君士坦丁堡。