Vertiginous \vur-TIJ-uh-nuhs\ , adjective;
1. Affected with vertigo; giddy; dizzy
2. Causing or tending to cause dizziness
3. Turning round; whirling; revolving
4. Inclined to change quickly or frequently; inconstant
This word dates to the 1600's from French vertigineux, which derives from Latin vertiginosus ("suffering from dizziness"). Vertiginosus comes from Latin vertigo (originally "a whirling or spinning movement," later "dizziness") from vertere ("to turn") which is, of course, the forebear of vertigo.
Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Saturday, May 28
Etymologies come from the Oxford English Dictionary and/or Etymonline.com