A bugaboo is a thing that makes people afraid or very worried — and often the fear is bigger than the thing. It can be a real problem people keep talking about, or a kind of monster in the mind. American English uses this more. It sounds informal, and a little old. People say the bugaboo of something about a public worry, like prices going up. Though actually, the speaker may think the fear is silly, or they may think it is the real thing that keeps people awake. It is not an insect. It is close to bugbear, but a bugaboo leans toward fear, and a bugbear leans toward this annoys me.

令人害怕或焦慮的事物（常帶一點「被嚇大了」的味道）