spoiler

One who spoils; a plunderer; a pillager; a robber; a despoiler.

One who corrupts, mars, or renders useless.

A document, review or comment that discloses the ending or some key surprise or twist in a story, or the internal rules controlling the behaviour of a video game, etc.

Good netiquette dictates that one warn of spoilers before discussing them, so that readers who wish to do so may experience the surprises for themselves.

Devotees of ‘expanded universe’ books say they will publish spoilers of latest film online unless Disney studio agrees to film their favourite stories

A device to reduce lift and increase drag.

A device to reduce lift and increase downforce.

To mark (a document or message) with a spoiler warning, to prevent readers from accidentally learning details they would prefer not to know.

To tell (a person) details of how a story ends etc.

I've been spoilered, so I doubt I'll be able to enjoy the final episode.