ˈpɒdəʊskæf

Podoscaph: A canoe-shaped float attached to the foot, for walking on water

The word is formed by attaching the Greek prefix pod(o)- (derived from pous, meaning “foot”) to skaphos, “ship”.

In the fifteenth century, Leonardo da Vinci toyed with podoscaph design—but, realizing that they wouldn’t be a particularly stable mode of locomotion, he sketched in a pair of ski-pole floats for his water-walker, too.

The little model built for the Macchine di Leonardo exhibition makes the design clearer, but no more convincingly stable.The Greek skaphos gave Auguste Piccard the name for his bathyscaphe (“deep ship”), the free-diving, deep-sea submersible that he designed in 1937, which he contrasted with Beebe and Barton’s earlier bathysphere (1934), which merely dangled from a cable.

And before moving on to other things, I can’t help but mention Jean Baptiste de La Chapelle‘s scaphander (“ship man”), a sort of cork jacket to aid locomotion in water. The illustration below, from his book Traité de la construction théorique et pratique du scaphandre, ou du bateau de l’homme (1775), speaks for itself. Though I’m not entirely sure what it’s saying.

A thing that looks like a ship is scaphoid. There’s a gently curved scaphoid bone in your wrist. (It has a Roman cousin in your foot—the navicular bone, from the Latin navicula, “little ship”.)

A feature of extreme malnutrition is a scaphoid abdomen. When a starved person lies flat, the abdomen sags inwards. The v-shape of the ribs above is the prow of this abdominal ship, the curve of the pelvic bones below is the stern, and the inward-sagging abdomen between resembles the hollow inside of the ship’s hull.

Now, back to the other half of podoscaph:

That combining form pod(o)-, for “foot”, gives us podiatry “foot surgery”. Chiropody, a different name for the same job, is a “factitious designation”, according to the Oxford English Dictionary. It’s not clear whether the inventor of the term meant to combine cheiro-, “hand”, with pous, “foot” (thereby suggesting chiropody should involve both the hands and feet) or was using the Greek cheiropodes, “having chapped feet”. Neither quite makes sense, but neither is quite nonsense, either.

There are a huge number of foot-related words ending either -pod (Greek) or -ped (Latin), which are hardly worth discussing individually. But it’s worth mentioning octopus (“eight foot”) and platypus (“flat foot”), which are both derived from Greek pous, “foot”. That -us at the end is a trap for the unwary, luring us into trying out a Latin plural form, after the fashion of cacti, fungi, nuclei and hippopotami—but “octopi” and “platypi” are just plain wrong. If you want a Classical plural, it needs to be Greek: octopodes (ɒkˈtəʊpədiːz) and platypodes (plæˈtɪpədiːz) are what’s required— each with four syllables, emphasis on the second syllable. Try it, by all means. But people will look at you strangely. There’s nothing wrong with forming standard English plurals instead: octopuses and platypuses.

The Greek -podes plural is familiar from antipodes, “opposite feet”—people on the opposite side of the world have their feet pointing towards us. But note that antipodes is singular: each location on the globe has only one antipodes, all to itself. It’s tempting to work backwards from octopus and platypus to come up with a truly singular antipodal form: “antipus”. (Well, I find it tempting.) But that would imply that there was only one person in the opposite side of the world from you, and that they had only one foot.