Definition: Anthrax refers to an invertebrate animal, a type of worm that causes human infections. Its Latin name, "anthrax," comes from the Greek for "worm." The word is a compound form of "ant-" (an old root) and "rhufin" (a prefix meaning "to scratch"). Definition: - Anthrax: Invertebrate animal, a type of worm that causes human infections. - Latin name: Ant- + rhufin - Greek for "worm," but it was originally used to describe the antler-like structure on an ant's back, similar to antlers.