Pachyderm is a term used to describe all those grey, thick-skinned giant mammals you usually see at the zoo, chiefly the rhinoceros, hippopotamus, and elephant. That quality of having thick skin is going to be important in a moment, so pay attention. We got the word in 1838 from French pachyderme, where it was used as a biological term to classify the animals. This in turn was taken from Greek pakhydermos, which translates to "thick-skinned", which makes sense for the aforementioned reason. Pakhydermos is a portmanteau of pakhys, meaning "large", and derma, that root pertaining to skin that we all recognize from the word dermatologist. Pakhys is reconstructed as coming from the Proto-Indo-European root beng, which could carry connotations of either "thick" or "fat". Derma, meanwhile, came from PIE der, which meant "to split", a definition that was connected to "skin" by an intermediate translation of "flay".
Adam Aleksic, a leading contender for valedictorian of his high school, is a 215-month-old boy with disturbing interests in etymology, vexillology, geography, and law. Adam would like to one day visit Tajikistan and probably isn't spying for the Uzbek government.
The Etymology Nerd