home r Michael Otero rat [rat] –noun 1. any of several long-tailed rodents of the family Muridae, of the genus Rattus and related genera, distinguished from the mouse by being larger. 2. any of various similar or related animals. 3. Slang. a scoundrel. a b c d e f g h i j k l m n o p q r s t u v w x y z rack rain ray rainbow raze radio read reach record recumbent rabbit red-rev rat