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1706, respelling of croisade (1570s), from Middle French croisade (16c.), Spanish cruzada, both from Medieval Latin cruciata, past participle of cruciare "to mark with a cross," from Latin crux (genitive crucis) "cross." Other Middle English forms were croiserie, creiserie. Figurative sense of "campaign against a public evil" is from 1786.
1732, from crusade (n.). Related: Crusaded; crusading.