Definitions for mockingbirdˈmɒk ɪŋˌbɜrd
Random House Webster's College Dictionary
any of several New World songbirds of the family Mimidae that appropriate the calls of other bird species, esp. Mimus polyglottos, of the U.S. and Mexico, having gray, white, and black plumage.
Origin of mockingbird:
mockingbird, mocker, Mimus polyglotktos(noun)
long-tailed grey-and-white songbird of the southern United States able to mimic songs of other birds
A long-tailed American songbird of the Mimidae family, noted for its ability to mimic calls of other birds.
The New Hacker's Dictionary
Software that intercepts communications (especially login transactions) between users and hosts and provides system-like responses to the users while saving their responses (especially account IDs and passwords). A special case of Trojan horse.