Bug

Chamber's Twientieth Century Dictionary · 1908 · p. 16

bug, n. an object of terror.— ns. Big-bug ( slang ), an aristocrat; Bug′aboo , a bogy, or object of terror; Bug′bear , an object of terror, generally imaginary.— adj. causing fright. [M. E. bugge , prob. W. bwg , a hobgoblin.]