Webster's Revised Unabridged Dictionary · 1913

Roarer

Roarer , noun

1.
One who, or that which, roars.
(a)
A riotous fellow; a roaring boy.
A lady to turn roarer, and break glasses. — Massinger
(b)
(Farriery) A horse subject to roaring. See Roaring, 2.
2.
(Zoology) The barn owl. [Provincial English]