The term crusade used in modern historiography at first referred to the wars in the Holy Land beginning in 1095, but the range of events to which the term has been applied has been greatly extended, so that its use can create a misleading impression of coherence, particularly regarding the early Crusades. The term used for the campaign of the First Crusade was iter "journey" or peregrinatio "pilgrimage". The terminology of crusading remained largely indistinguishable from that of pilgrimage during the 12th century, reflecting the reality of the first century of crusading where not all armed pilgrims fought, and not all who fought had taken the cross. It was not until the late 12th to early 13th centuries that a more specific "language of crusading" emerged. Pope Innocent III used the term negotium crucis "affair of the cross" for the Eastern Mediterranean crusade, but was reluctant to apply crusading terminology to the Albigensian crusade. The Song of the Albigensian Crusade from about 1213 contains the first recorded vernacular use of the Occitan crozada. This term was later adopted into French as croisade and in English as crusade. The modern spelling crusade dates to c. 1760. Sinibaldo Fieschi (the future pope Innocent IV) used the terms crux transmarina for crusades in Outremer against Muslims and crux cismarina for crusades in Europe against other enemies of the church.
The Crusades in the Holy Land are traditionally counted as nine distinct campaigns, numbered from the First Crusade of 1095–99 to the Ninth Crusade of 1271–72. This convention is used by Charles Mills in his History of the Crusades for the Recovery and Possession of the Holy Land (1820) and is often retained for convenience even though it is somewhat arbitrary. The Fifth and Sixth Crusades led by II may be considered a single campaign, as can the Eighth Crusade and Ninth Crusade led by IX.
The Arabic loanword Muslim is first attested in English in the 17th century. Before this the common term for Muslim was Saracen, in origin referring to the pre-Islamic, non-Arab inhabitants of the desert areas around the Roman province of Arabia. The term evolved to include Arab tribes, and by the 12th century it was an ethnic and religious marker in Medieval Latin literature corresponding to modern "Muslim".
Frank and Latin were used during the Crusades for Western Europeans, distinguishing them from Greeks. Crusader sources used the term Syrians to describe Arabic speaking Christians who were members of the Greek Orthodox Church and Jacobites for those who were members of the Syrian Orthodox Church
The term used in modern Arabic, ḥamalāt ṣalībiyya حملات صليبية, lit. "campaigns of the cross", is a loan translation of the term Crusade as used in Western historiography.