To go off half-cocked means to act prematurely, to speak prematurely. To go off half-cocked is another idiom derived from the operation of firearms. To fire a flintlock gun, one must pull back the cock, or striker. When a gun is fully cocked, it is ready to fire. When a gun is half-cocked, it is not ready to fire. If one shoots with a half-cocked gun, the result will not be satisfactory. This fact translated into an idiom that describes someone speaking or acting in a manner that is premature, before weighing all factors or being fully prepared. Related phrases are goes off half-cocked, went off half-cocked, going off half-cocked. To go off half-cocked is the North American version of the idiom.





To go off at half-cock is the British version of the idiom, the definition remains the same.