Definitions:
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.

a dominican friar.

a pigeon of a breed with reversed feathers on the back of its neck like a cowl.

a mainly green central and south american hummingbird, with blue feathers on the head.