Jacobin

UK: /ˈdʒækəbɪn/ US: ( jak′ə bin)

WordReference Random House Unabridged Dictionary of American English © 2025

Jac•o•bin  ( jak′ə bin), n. 

1. World History (in the French Revolution) a member of a radical society or club of revolutionaries that promoted the Reign of Terror and other extreme measures, active chiefly from 1789 to 1794: so called from the Dominican convent in Paris, where they originally met.
2. World History an extreme radical, esp. in politics.
3. Religion a Dominican friar.
4. (l.c.) one of a fancy breed of domestic pigeons having neck feathers that hang over the head like a hood.

• Medieval Latin (frater) Jacōbinus. See Jacob, -in¹
• Old French (frere) jacobin
• Middle English Jacobin 1275–1325

Jac′o•bin′ic, Jac′o•bin′i•cal, adj. 
Jac′o•bin•ism, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

Jacobin / ˈdʒækəbɪn/ noun

1. a member of the most radical club founded during the French Revolution, which overthrew the Girondists in 1793 and, led by Robespierre, instituted the Reign of Terror
2. a leftist or extreme political radical
3. a French Dominican friar

adjective

1. of, characteristic of, or relating to the Jacobins or their policies

Etymology: 14th Century: from Old French, from Medieval Latin Jacōbīnus, from Late Latin Jacōbus James; applied to the Dominicans, from the proximity of the church of St Jacques (St James) to their first convent in Paris; the political club originally met in the convent in 1789

ˌJacoˈbinic, ˌJacoˈbinical adjective

ˈJacobinism noun