Pachyderm

Pachyderm (pronounced pak-i-durm)

(1) Historically, any of the thick-skinned, non-ruminant ungulates, such as the elephant, hippopotamus, and rhinoceros.

(2) General (non-scientific) term for an elephant and some other, impressively large creatures.

(3) In the idiomatic, a person not sensitive to criticism, ridicule, etc; a thick-skinned person.

1838: From the seventeenth century French pachyderme, from the New Latin Pachyderma, the assumed singular of Pachydermata, from the Ancient Greek pakhudermos (thick-skinned), the construct being of pakhus (thick, large, massive) + derma (skin (from the primitive Indo-European root der (to split, flay, peel) with derivatives referring to skin and leather)).  The more familiar form of derma was dérmata, neuter plural of dermatos (skinned).  Pachyderme was in 1797 adopted as a biological term in 1797 by French naturalist Jean Léopold Nicolas Frédéric (Baron (Georges) Cuvier, 1769–1832) and while the order Pachydermata has fallen into disuse in formal zoology, pachyderm remains in common use to describe elephants, rhinoceroses, hippopotamuses etc.  The related forma are pachydermal, pachydermous, pachydermic, pachydermoid & pachydermatous.

Elephants

In zoology, the original taxonomic order, Pachydermata (“thick skin” the construct from the Ancient Greek being παχύς (pachys) (thick) + δέρμα, (derma) (skin) is a now obsolete order of mammals, a grouping which once included thick-skinned, hoofed animals such as the rhinoceros, hippopotamus, elephant, pig and horse.  Being polyphyletic, the order is no longer used but is an illustrative cul-de-sac in the history of systematics.  The word “pachyderm” remains in use to describe elephants, rhinoceroses, tapirs, and hippopotamuses.

The original classification Pachydermata included three herbivorous families: Proboscidiana, Pachydermata Ordinaria, and Solipedes.  They were later reclassified as Proboscidea (among living species represented now only by three species of elephants), the Perissodactyla (odd-toed ungulates, including horses, tapirs and rhinoceroses), the Suina (pigs and peccaries), the Hippopotamidae, and the Hyracoidea (hyraxes).  It was advances in genetic analysis which allowed the others to be classified as wholly separate clades.

Interestingly, despite the name being a reference to the thickness of skin, the thin-skinned horse genus was an original inclusion, based apparently on the other shared characteristic: "mammals with hoofs with more than two toes".  Belying appearances, horses do exhibit a slight departure from a true monodactylous structure, every member of the family having vestiges of two additional toes under the skin.

A pachyderm playing polo.

Chrysler’s 426 cubic inch (7.0 litre) Street Hemi V8 (1966-1971), was nicknamed “Elephant Motor”, an allusion to the bulky cylinder heads required to house the complex valve-train and their vague resemblance to ears of the beast.  The moniker was a piece of zoological one-upmanship on Chevrolet's mouse (small-block V8) and rat (big block V8).

Failures in verisimilitude in Mean Girls (2004):  One of the props was a framed photograph representing Cady Heron during her childhood in Africa, sitting atop an elephant.  The elephant of a different taxonomy, being an Asian elephant (Elephas maximus) instead of the appropriate African savanna bush elephant (Loxodonta africana) known in Kenya.  The left hand's inadvertent srpski pozdrav (a three-fingered Serbian salute originally expressing the Holy Trinity and used in rituals of the Orthodox Church which has (like much in the Balkans) been re-purposed as a nationalist symbol) is a Photoshop fail.