Underwing
Pronunciation : Un"der*wing`
Part of Speech : n.
Definition : 1. (Zo?l.)
Defn: One of the posterior wings of an insect.
2. (Zo?l.)
Defn: Any one of numerous species of noctuid moths belonging to Catocala and allied genera, in which the hind wings are banded with red and black or other conspicuous colors. Many of the species are called red underwing.
Source : Webster's Unabridged Dictionary, 1913
Merriam-Webster's Everyday Language Reference Set: Includes: The Merriam-Webster Dictionary, The Merriam-Webster Thesaurus, and The Merriam-Webster Vocabulary Builder