The Collaborative International Dictionary of English v.0.48:
mockingbird \mockingbird\, mocking bird \mocking bird\n.
A long-tailed gray-and-white songbird of North America
(Mimus polyglottos), remarkable for its exact imitations of
the notes of other birds. Its back is gray; the tail and
wings are blackish, with a white patch on each wing; the
outer tail feathers are partly white. Originally its range
was confined mostly to the southern states, but by late 19th
century it had migrated as far north as New York. The name is
also applied to other members of thee same and related
genera, found in Mexico, Central America, and the West
Indies, such as the blue mockingbird of Mexico, Melanotis
Syn: mocker, Mimus polyglottos .