Lemming

Tribe of rodents of the family Cricetidae

A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae together with voles and muskrats, which form part of the superfamily Muroidea, which also includes rats, mice, hamsters and gerbils. In popular culture, a longstanding myth holds that they exhibit herd mentality and jump off cliffs, committing mass suicide.

This keyword could refer to multiple things. Here are some suggestions: