A Jacobin (French pronunciation: ​[ʒakɔbɛ̃]; English: ) was a member of the Jacobin Club, a revolutionary political movement that was the most famous political club during the French Revolution (1789–1799). The club got its name from meeting at the Dominican rue Saint-Honoré Monastery of the Jacobins. The Dominicans in France were called Jacobins (Latin: Jacobus, corresponds to Jacques in French and James in English) because their first house in Paris was the Saint Jacques Monastery.

The terms Jacobin and Jacobinism have been used in a variety of senses. Prior to 1793, the terms were used by contemporaries to describe the politics of Jacobins in the congresses of 1789 through 1792. With the ascendancy of Maximilien Robespierre and the Montagnards into 1793, they have since become synonymous with the policies of the Reign of Terror, with Jacobinism now meaning "Robespierrism." As Jacobinism was memorialized through legend, heritage, tradition and other nonhistorical means over the centuries, the term acquired a "semantic elasticity" in French politics of the late 20th Century with a "vague range of meanings," but all with the "central figure of a sovereign and indivisible public authority with power over civil society." Today in France, Jacobin colloquially indicates an ardent or republican supporter of a centralized and revolutionary democracy or state as well as "a politician who is hostile to any idea of weakening and dismemberment of the State."