from the GNU version of the Collaborative International Dictionary of English
- transitive v. To set the cock of (a firearm) at the first notch.
from The Century Dictionary and Cyclopedia
- To cock the hammer of, as a gun, so that it rests at the first notch.
- n. The position of the cock or hammer of a gun when it is elevated only half-way and retained by the first notch. See cock.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. confusion resulting from lack of preparation
Sorry, no etymologies found.
Gee, usually you're the one that keeps me from going off at halfcock.
There you are; that is characteristic of laymen, going off at halfcock.