pachy-

Thick.

Greek pakhus, thick.

A pachyderm (Greek derma, skin) is a very large mammal with thick skin, such as an elephant, rhinoceros, or hippopotamus, while pachyderma is a condition in which the skin becomes thickened; a pachymeter is a device for measuring the thickness of thin structures, especially the cornea of the eye; a pachycephalosaur (Greek kephalē, head, plus sauros, lizard) is a bipedal herbivorous dinosaur of the late Cretaceous period, with a thick domed skull.