Possible Definitions:
1. Bugbear (n.) Something frightful, as a specter; anything imaginary that causes needless fright; something used to excite needless fear; also, something really dangerous, used to frighten children, etc.
2. Bugbear (n.) Same as Bugaboo.
3. Bugbear (a.) Causing needless fright.
4. Bugbear (v. t.) To alarm with idle phantoms.