What does "bugbear" mean?

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. "Bugaboos to fright ye." Lloyd. But, to the world no bugbear is so great As want of figure and a small estate. Pope. The bugaboo of the liberals is the church pray. S. B. Griffin. The great bugaboo of the birds is the owl. J. Burroughs.

Additional senses

  1. 2.Same as Bugaboo. -- a. Causing needless fright. Locke.
  2. 3.To alarm with idle phantoms.

Sources