Webster's Revised Unabridged Dictionary · 1913

jinx

jinx (jinks) , noun

A person, object, influence, or supernatural being which is supposed to bring bad luck or to cause things to go wrong. [Slang]

jinx (jinks) , transitive verb

To bring bad luck to; to cause to malfunction or go wrong; as, some superstitious people are reluctant to predict success for fear it will jinx them. [Slang]