'ammonoidean' originates from the Greek word 'ammōn,' referring to the Egyptian god Ammon, whose ram's horns resemble the coiled shells of these creatures.

'ammonoidean' changed from the Greek word 'ammōn' to the Latin 'ammonites,' and eventually became the modern English word 'ammonoidean.'

Initially, it referred to the resemblance to the ram's horns of Ammon, but over time it evolved into its current meaning of a subclass of extinct marine mollusks.