From BiblePortal Wikipedia

The Nuttall Encyclopedia [1]

A political club, originally known as the Club Breton, which was founded in Paris during the French Revolution; so called from its place of meeting in the Rue St. Honoré, which had previously been a Jacobin friar convent; it exercised a great influence over the course of the Revolution, and had affiliated societies all over the country, working along with it; its members were men of extreme revolutionary views, procured the death of the king, exterminated the Girondists, roused the lowest classes against the middle, and were the ruling spirits during the Reign of Terror, of whom Robespierre was the chief, the fall of whom sealed their doom; they were mobbed out of their place of meeting with execrations on Hallow-Eve 1794.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [2]

a name applied in France to the Dominicans (q.v.), because their principal convent was situated near the gate of St. James (Jacobus), in Paris. At the commencement of the first French revolution the meetings of its most zealous promoters were. held in the hall of this convent, and from this circumstance Jacobin came to be another name for revolutionist.