bugaboo (n.)

"something to frighten a child, fancied object of terror," 1843, earlier buggybow (1740), probably an alteration of bugbear (also see bug (n.)), but connected by Chapman ["Dictionary of American Slang"] with Bugibu, demon in the Old French poem "Aliscans" from 1141, which is perhaps of Celtic origin (compare Cornish bucca-boo, from bucca "bogle, goblin").

updated on August 23, 2017

Definitions of bugaboo from WordNet

bugaboo (n.)
an imaginary monster used to frighten children;
Synonyms: bogeyman / bugbear / boogeyman / booger
bugaboo (n.)
a source of concern;
the old bugaboo of inflation still bothers them
From, not affiliated with etymonline.