The adjective pachydermatous means "of or relating to the pachyderms" or "thickened" (referring to skin). Not too surprisingly, it also means "callous" or "insensitive" (somewhat unfairly to elephants, which are actually known to be rather sensitive).

What part of speech is pachyderm?

pachyderm ​Definitions and Synonyms

​noun countable. UK /ˈpækiˌdɜː(r)m/ singular.

What is a pachyderm?

The term pachyderm (meaning thick-skinned animals) is the original classification for elephants, hippopotamuses, rhinoceroses, pigs and tapirs. Wilhelma's pachyderms live in two houses, the Elephant House and the Tapir House.