1. a two-piece clothes fastener, usually of metal, consisting of a hook that catches onto a loop or bar.
2. a three-piece latching device consisting of a hook attached to a screw eye or an eyebolt and a separate screw eye or eyebolt that the hook engages as it bridges a gap, as one between a door and a jamb or a gate and a gatepost.
3. Also calledeyehook. the two-piece portion of such a device consisting of a hook and a screw eye.