反犹太主义是一种意识型态，对于对仇恨犹太人或犹太教的思想与行为的总称，在各个不同历史时期有不同的动机和表现形式。反犹太主义不仅在基督徒有，在欧洲人、亚洲人及阿拉伯人也有。

「反犹太主义」的原文（英语：Antisemitism、Anti-Semitism 或 anti-semitism）直译为反闪族主义。在字面意义上，反闪族主义是对于所有闪族的反感情绪，虽然犹太人与阿拉伯人同属闪米特人，但是这个名词在欧洲特指对于犹太人的仇恨情绪。这个名词在1873年首次在德国出现，同义词是「仇恨犹太人者」（德语：Judenhass，英语：Jew-hatred）。

Antisemitism (also spelled anti-Semitism or anti-semitism) is hostility, prejudice or discrimination against Jews. A person who holds such positions is called an antisemite. Antisemitism is widely considered to be a form of racism.

The root word Semite gives the false impression that antisemitism is directed against all Semitic people. However, the compound word antisemite was popularized in Germany in 1879 as a scientific-sounding term for Judenhass (Jew-hatred), and that has been its common use since then.