noun

• (Christianity, dated) Synonym of Dominican, a member of the Dominican Order, particularly its French chapter.
• (historical) A member of the Jacobin Club, a radical political club prominent during the French Revolution.
  "The Jacobins acted as a left-of-centre parliamentary pressure group, spending much of their time in coordinating the following day's business in the Assembly."
• (historical, by extension) A sympathizer or supposed sympathizer with the French political club or its aims of democracy and social equality.
• (by extension) A leftist radical in other contexts.

adj

• (historical) Of or related to the Jacobin Club in France.
• (by extension) Of or related to the radical left in other contexts.
  "[…] Mosse argued the most fascist and totalitarian in particular but also radical Jacobin regimes, continued to have an investment in not merely disciplining human bodies but harnessing their sense of glory toward worshiping themselves […]"
• (Christianity, dated) Synonym of Dominican, of or related to the Dominican Order, particularly its French chapter.
• (Christianity, archaic) Synonym of Jacobite, of or related to the Syriac Orthodox Church.

noun

• (obsolete) A kind of thick French soup with cheese.