A superstitious term meaning to give something bad luck or misfourtune
“He hadnt got a bad grade all year, but by mentioning that to his friend he jinxed it.”
verb: jinx; 3rd person present: jinxes; past tense:jinxed; past participle: jinxed; gerund or present participle: jinxing
i.e. bring bad luck to; cast an evil spell on.
“the play is jinxed”