crusade (n.) Look up crusade at Dictionary.com
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.
crusade (v.) Look up crusade at Dictionary.com
1732, from crusade (n.). Related: Crusaded; crusading.