horizontal gaze nystagmus test

noun | \ -ni-ˈstag-məs- \ | horizontal gaze ny·stag·mus test
  1. : a test for intoxication (as of a driver) based on observation of involuntary jerking movements of the eyes as they follow horizontal motion

    Note: This test is one of several usually administered by police officers to determine the sobriety of a suspected drunk driver.