(neurology, psychiatry) A condition in which a person experiences their limbs acting seemingly on their own, without control over the actions.

plural of alien hand syndrome

(fandom slang) An implausible point of divergence from reality, used as a plot device in alternate history.

The state or status of being alien.

(slang) A sarcastic assertion that something that has not been satisfactorily explained by science is therefore evidence of extraterrestrial life on Earth.