jacobin

1. a member of a democratic club established in Paris in 1789. The Jacobins were the most radical and ruthless of the political groups formed in the wake of the French Revolution, and in association with Robespierre they instituted the Terror of 1793–4.
2. a Dominican friar.
3. a pigeon of a breed with reversed feathers on the back of its neck like a cowl.
4. a mainly green Central and South American hummingbird, with blue feathers on the head.

Middle English (in Jacobin (sense 2)): from Old French, from medieval Latin Jacobinus, from ecclesiastical Latin Jacobus ‘James’. The term was applied to the Dominicans in Old French on account of their church in Paris, St Jacques, near which they built their first convent; the latter eventually became the headquarters of the French revolutionary group.