mourning cloak

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A nymphalid butterfly (Nymphalis antiopa) of Eurasia and North America, having purplish-brown wings with a broad yellow border.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun obsolete A dark cloak worn by a mourner at a funeral.
• noun US A large butterfly, Nymphalis antiopa, native to Eurasia and North America.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun of temperate regions; having dark purple wings with yellow borders