Pachydermic is an adjective used to describe thick, tough skin, as typically found on the elephant and other large mammals. There are several synonyms that can be used to describe the same thing. One of the most commonly used synonyms is thick-skinned, which refers to having an insensitive or unfeeling nature. Another option is tough-skinned, which has a similar meaning to pachydermic and suggests durability and endurance. Other synonyms for pachydermic include calloused, hardened, and insensitive. All of these words can be used to convey the same meaning as pachydermic, but with slight variations in connotation.