AI doomer means: Someone who genuinely believes AI is about to kill everyone - that ASI will arrive, fail to align, and cause human extinction. Often associated with LessWrong, MIRI, and the rationalist diaspora.. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.