LEMMING

[noun] [C] - an animal that looks like a large mouse and lives in cold northern areasLemmings migrate (= move from one place to another) in large groups, and are often thought (wrongly) to jump off cliffs together, so groups of people who all do something foolish together without thinking for themselves can be called lemmings.People rushed like lemmings to invest their money in the company that later went bankrupt.