[boo l-rawr-er, -rohr-]
  1. a wooden slat that produces a roaring sound when whirled around one's head on the end of a string or thong, used by some peoples of the world in religious ceremonies and by others as a toy.

Origin of bull-roarer

First recorded in 1880–85
Also called thunderstick.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for bull-roarer

Historical Examples of bull-roarer