A thick-skinned mammal is a type of animal that has a thick hide or skin, usually for protection. The four crossword solutions for this term are Rhino (5 letters), PACHYDERM (9 letters), ELEPHANT (8 letters), and HIPPO (5 letters). The Rhino is a large mammal with a thick, gray hide and two horns on its snout. Pachyderms are a group of mammals that includes the Rhino, ELEPHANT, and HIPPO, all of which have thick skin. The ELEPHANT is the largest land mammal and has a thick, gray hide. The HIPPO is a large, semi-aquatic mammal with a thick, gray hide and short legs.