WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
an evil spirit
noun.
an unidentified (and possibly enemy) aircraft
Word Usage
"Bugaboo is from the archaic term bogy boo -- a term for a hobgoblin or anything that haunts, bothers, bugs, harasses, irks, annoys, or frightens, like the bogeyman."