A wallaroo is any of three closely related species of moderately large macropod, intermediate in size between the kangaroos and the wallabies. The word "wallaroo" is a portmanteau of "wallaby" and "kangaroo". In general, a large, slim-bodied macropod of the open plains is called a "kangaroo"; a small to medium-sized one, particularly if it is relatively thick-set, is a "wallaby": most wallaroos are only a little smaller than a kangaroo, fairly thickset, and are found in open country.