- The definition of forbidden is something that is not allowed.
An example of something forbidden is opening a door that your parent has told you not to touch.
forbidden definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
not permitted; prohibited
forbidden definition by American Heritage Dictionary
A past participle of forbid.adjective Physics
Having an extremely low probability of occurrence. Used of quantum phenomena: a forbidden transition.
Variant of forbid