Bugbear

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.

Same as Bugaboo.

Causing needless fright.

To alarm with idle phantoms.

an object of dread or apprehension; "Germany was always a bugbear for France"; "A foolish consistency is the hobgoblin of little minds" - Ralph Waldo Emerson