Vertigo is the horrible spinning feeling you get when you look down from somewhere very high — the ground seems to pull at you, your head swims, and you may feel sick. Everyday English uses it exactly that way: "I get vertigo on ladders." But it is worth knowing that doctors use the word more narrowly and more seriously. To a doctor, vertigo is the illusion that you or the room is spinning, and it usually comes from a problem in the inner ear, not from height at all. Someone with that condition can wake up and feel the bedroom turning, lying flat, with no high place anywhere. So the same word covers a passing feeling on a cliff and a real medical illness. It is uncountable — say *vertigo*, *some vertigo*, never *a vertigo*. Many people also know it as the title of a famous Hitchcock film, where the hero's fear of heights drives the whole story.