Specifically, a crook is a tool with a crook in it, such as a shepherd's staff or prelate's crosier; see also flail and crook.
In music, a crook is a length of tubing used to change the pitch of a natural horn or other brass instrument; by removing one crook of a given length and replacing it with a crook of another, the entire pitch of the instrument would change.
A crook is also the term for a bent or curved pipe that connects the reed to the instrument body on some double reed instruments; in American usage this is generally called a bocal.
For example, flails used by farmers in Quebec to process wheat were generally made from two pieces of wood, the handle being about 1.5 m long by 3 cm in diameter, and the second stick being about 1 m long by about 3 cm in diameter, with a slight taper towards the end.
Flails have generally fallen into disuse in many nations because of the availability of technologies such as combine harvesters that require much less manual labour.
Probably because of its use in judiciary flagellation, the flail is depicted along side the shepherd’s “crook” as symbols of office for the crowned Egyptian Pharaoh, likely representing the living God's authority to judge and punish his subjects.