A crook is a dishonest person or a criminal.

The crook of your arm or leg is the soft inside part where you bend your elbow or knee.

If you crook your arm or finger, you bend it.

A crook is a long pole with a large hook at the end. A crook is carried by a bishop in religious ceremonies, or by a shepherd.

If someone says they will do something by hook or by crook, they are determined to do it, even if they have to make a great effort or use dishonest means.