kink

Curl tightly.

Form a curl, curve, or kink.

A painful muscle spasm especially in the neck or back (`rick' and `wrick' are British).

A sharp bend in a line produced when a line having a loop is pulled tight.

A difficulty or flaw in a plan or operation.

“there are still a few kinks to iron out”

An eccentric idea.

A person with unusual sexual tastes.