Pachyderm

The Pachyderms were an obsolete artificial taxonomic grouping of several kinds of large, thick-skinned (hence the name) mammals, including the elephants, hippopotamuses, rhinoceroses, tapirs, peccaries and pigs

As the grouping was based on superficial similarities rather than any real kinship, it no longer enjoys any scientific currency, but the term is still occasionally used to refer, often humorously, to some of the larger and more impressive members of the grouping.