Vertigo is not a diagnosis it is a symptom. The Vestibular Disorders Association uses the following terminology to define vertigo: Spinning or whirling sensation; an illusion of movement of self or the world.
I have witnessed individuals with intense nystagmus describe their dizziness as other sensations than spinning. The presence of nystagmus often represents either a central or peripheral vestibular disorder. I see people all the time who have vestibular disorders (with nystagmus) and they describe their dizziness as lightheadedness, off balance, funny in the head, etc. Many clients I see who have been told they have vertigo do not truly have vertigo.
I have had clients with the diagnosis of Benign Paroxysmal Positional Vertigo present with typical BPPV nystagmus and describe their dizziness as lightheaded...not vertigo.