There's a word for that!...of the day
So we've all done it. We've walked up to the edge of a cliff, or peered off a tower or bridge, and got the willies! Your legs shake, your stomach reorients itself in a more twisted fashion, the palms of your hands get clammy, and you wait for someone to say that word. The word that always comes up... it might be you, or someone cowering from the edge refusing to look over claiming: "I can't, I have vertigo...I'm a afraid of heights!"
The word you were looking for, in your moment of panic, isn't Vertigo. Vertigo is actually a medical condition that causes loss of balance and a feeling of falling in some cases. It's understandable then to attribute this condition to the panic reflex you get when you dangle precariously from a height...but the word you're really looking for here is simply "Acrophobia".
Think about the fact that all phobias are Greek-based and the term for "High" or "Heights" is Acro, like the High Court - The Acropolis.
So that's that, the fear of heights is acrophobia, and just remember, it's not the height you're afraid of, it's the fall. Then again, it's never the fall that kills'ya, it's that sudden stop at the end!
Cheers to the English language and all our misuses of it!