hook

• curved piece of metal or other material by which things are hung or attached; fishhook; curve, angle, sharp bend; short punch (boxing)
secure, fasten, hang, attach; bend; capture; ensnare, addict; catch a fish; be caught; be attached; pull loops of yarn through cloth with a hook; steal (slang); punch with the elbow bent (boxing)
a hook is a bent piece of metal or plastic used for holding things or hanging things on.
if you hook one thing onto another, you attach it there using a hook.
see also hooked.
if you take the phone off the hook, you take the receiver off the part that it normally rests on, so that the phone will not ring.
if your telephone is ringing off the hook, so many people are trying to telephone you that it is ringing constantly; used in american english.
if someone gets off the hook, they manage to get out of a difficult or dangerous situation; an informal expression.
if you hook up a computer or other electronic machine, you connect it to other similar machines or to a central power supply.