dizziness Painless head discomfort with many possible causes, including disturbances of vision, the brain, the balance (vestibular) system of the inner ear, or the gastrointestinal system. Dizziness is a medically indistinct term. Laypersons use it to describe a variety of conditions, ranging from lightheadedness or unsteadiness to vertigo. See also lightheadedness; unsteadiness; vertigo.
