Webster's 1913 Dictionary
BUGABOO; BUGBEAR
Bug `a *boo ", Bug "bear `, n. Etym: [See Bug. ]
Defn: 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.
Syn. -- Hobgoblin; goblin; specter; ogre; scarecrow.
New American Oxford Dictionary
bugaboo
bug a boo |ˈbəgəˌbo͞o ˈbəɡəˌbu | ▶noun an object of fear or alarm; a bugbear. ORIGIN mid 18th cent.: probably of Celtic origin and related to Welsh bwci bo ‘bogey, the Devil, ’ bwci ‘hobgoblin ’ and Cornish bucca.
Oxford Dictionary
bugaboo
bugaboo |ˈbʌgəbuː | ▶noun chiefly N. Amer. an object of fear or alarm; a bogey. ORIGIN mid 18th cent.: probably of Celtic origin and related to Welsh bwci bo ‘bogey, the Devil ’, bwci ‘hobgoblin ’ and Cornish bucca.
Sanseido Wisdom Dictionary
bugaboo
bug a boo /bʌ́ɡəbùː /名詞 複 ～s C ｟米 やや古 ｠(想像上の )恐怖の種 ; お化け .
The Wordsmith Dictionary