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Etymology

The name "sperm whale" is a clipping of "spermaceti whale". Spermaceti, originally mistakenly identified as the whales' semen, is the semi-liquid, waxy substance found within the whale's head. (See " Spermaceti organ and melon " below.)

The sperm whale is also known as the "cachalot", which is thought to derive from the archaic French for 'tooth' or 'big teeth', as preserved for example in the word caishau in the Gascon dialect (a word of either Romance or Basque origin).

The etymological dictionary of Corominas says the origin is uncertain, but it suggests that it comes from the Vulgar Latin cappula 'sword hilts'. The word cachalot came to English via French from Spanish or Portuguese cachalote, perhaps from Galician /Portuguese cachola 'big head'.

The term is retained in the Russian word for the animal, kashalot (кашалот), as well as in many other languages.

The scientific genus name Physeter comes from the Greek physētēr (φυσητήρ), meaning 'blowpipe, blowhole (of a whale)', or – as a pars pro toto – 'whale'.

The specific name macrocephalus is Latinized from the Greek makroképhalos (μακροκέφαλος 'big-headed'), from makros (μακρός) + kephalē (κεφαλή).

Its synonymous specific name catodon means 'down-tooth', from the Greek elements cat(a)- ('below') and odṓn ('tooth'); so named because it has visible teeth only in its lower jaw. (See " Jaws and teeth " below.)

Another synonym australasianus (' Australasian ') was applied to sperm whales in the Southern Hemisphere.