فِرْنِبٌ A rat, or mouse; syn. فَأْرَةٌ: (IAạr, O, Ḳ:) or the young one generated between it and a jerboa: (Ḳ:) or [as a coll. gen. n.] the rat, or mouse; syn. فَأْرٌ. (T.) [See also قَرْنَبٌ.]