The American Heritage® Dictionary of the English Language, 4th Edition
n. Any of various Old World carnivorous mammals of the genus Herpestes and related genera, having a slender agile body and a long tail and noted for the ability to seize and kill venomous snakes.
n. Carnivores of the family Herpestidae and the similar Malagasy mongooses (Galidiinae), ranging in size from small rats to large cats, including the Indian mongoose famed as a predators of venomous snakes.
the GNU version of the Collaborative International Dictionary of English
n. A species of ichneumon (Herpestes griseus), native of India. Applied also to other allied species, as the African banded mongoose (Crossarchus fasciatus).
n. A Madagascan lemur (Lemur mongos).
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. agile grizzled Old World viverrine; preys on snakes and rodents
Word Usage
"That thing about the plural of the word mongoose, before we get to the real stuff, Doug in Connecticut says, "I once asked my father the correct plural of mongoose."