Functional Dizziness is a clinical construct within the category of chronic vestibular disorders that is characterized by persistent or recurrent dizziness, unsteadiness, or non-spinning vertigo in the absence of structural neurological pathology, where symptoms are disproportionately triggered or worsened by upright posture, self-motion, or exposure to complex visual stimuli, reflecting a dysfunction of central nervous system sensorimotor integration and cognitive-affective modulation rather than a direct organic vestibular lesion.