1.That which curbs, restrains, or subdues; a check or hindrance; esp., a chain or strap attached to the upper part of the branches of a bit, and capable of being drawn tightly against the lower jaw of the horse. "He that before ran in the pastures wild Felt the stiff curb control his angry jaws." "By these men, religion,that should be The curb, is made the spur of tyranny."
2.(Arch.) An assemblage of three or more pieces of timber, or a metal member, forming a frame around an opening, and serving to maintain the integrity of that opening; also, a ring of stone serving a similar purpose, as at the eye of a dome.
3.A frame or wall round the mouth of a well; also, a frame within a well to prevent the earth caving in.
5.(Far.) A swelling on the back part of the hind leg of a horse, just behind the lowest part of the hock joint, generally causing lameness.
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