Find the word definition

Wiktionary
cock ring

alt. a band worn around the base of the penis to slow down the flow of blood into the penile tissue. n. a band worn around the base of the penis to slow down the flow of blood into the penile tissue.

Wikipedia
Cock ring

A cock ring is a ring that can be placed around a penis, usually at the base, primarily to slow the flow of blood from the erect penile tissue, thus maintaining an erection for a much longer period of time.

Cock rings can be worn around just the penis or both the penis and scrotum, or just the scrotum alone, though this is usually called a testicle cuff. Rings can be made of a variety of different materials, most commonly leather, rubber, or silicone, though nylon and metal are also used either as the main component or part of the closure.

When used in cases of erectile dysfunction they are known by various names such as "erection ring" and "tension ring".