The word "Saracen" (/ˈsærəsən/ SARR-ə-sən) was commonly used in medieval Europe to refer to a person who lived in or near what the ancient Romans knew as Arabia Petraea and Arabia Deserta.^[1][2][3] Its original meaning in Greek and Latin is not known with certainty. By the early medieval period, it had come to be associated with the Arabian tribes.^[4] Following the rise of Islam, which occurred in Arabia, the word's definition evolved to refer not only to Arabs, but to Muslims as well. It eventually became the standard adjective among European Christians for all people and things from the Muslim world, regardless of whether they were Arab in origin.

The oldest known source mentioning "Saracens" in association with Muslims is the Greek-language Christian tract Doctrina Jacobi, which was compiled in the Byzantine Empire amidst the Muslim conquest of the Levant.^[5] The word became particularly widespread in European societies during the Crusades, when it was used by the Roman Catholic Church and by several European Christian political and military figures.

By the 12th century, "Saracen" had developed various overlapping definitions that generally conflated peoples and cultures in the Abbasid Caliphate, comprising all those in the Near East and beyond. Such an expansion in its meaning had begun centuries earlier, as evidenced in a number of 8th-century Byzantine documents in which Muslims are called Saracens.^[1][6][7] Before the 16th century, "Muslim" and "Islam" were generally not used in European discourse, with a few isolated exceptions;^[8] "Saracen" was gradually rendered obsolete amidst the Age of Discovery, whereafter "Mohammedan" became commonplace, though it also fell out of use by the 20th century and is now considered a misnomer or impertinent by many Muslims because it may suggest that they worship Muhammad rather than God.