A mongoose is a small terrestrial carnivorous mammal belonging to the family Herpestidae. The English word "mongoose" used to be spelled "mungoose" in the 18th and 19th centuries. The name is derived from names used in India for Herpestes species: muṅgūs or maṅgūs in classical Hindi.

The form of the English name (since 1698) was altered to its "-goose" ending by folk etymology. The plural form is "mongooses".

Mongooses have long faces and bodies, small, rounded ears, short legs, and long, tapering tails. Most are brindled or grizzly; a few have strongly marked coats which bear a striking resemblance to mustelids. Their nonretractile claws are used primarily for digging. Most species have a large anal scent gland, used for territorial marking and signaling reproductive status.
They range from 9.4 to 22.8 inches in head-to-body length, excluding the tail.

Mongooses are one of at least four known mammalian taxa with mutations in the nicotinic acetylcholine receptor that protect against snake venom. Their modified receptors prevent the snake venom α-neurotoxin from binding. These represent four separate, independent mutations.

These photos were taken in Hawaii.