Dic: bugaboo

• The old bugaboo of inflation still bothers them.
• Boredom, laziness and failure . . . These bugaboos, magnified by imagination, keep [the workaholic] running. (Dun's Review)
• The bugaboos that have plagued vision systems: high price and slow throughput. (Lawrence A. Goshorn)

1. (1) An object of obsessive, usually exaggerated fear or anxiety. | (2) A recurring or persistent problem.
2. NAmE. (informal) a thing that people are afraid of.

... The American Heritage, OALD