'amphistomous' originates from Greek, specifically the word 'amphistomos,' where 'amphi-' meant 'both' and 'stoma' meant 'mouth.'

'amphistomos' changed from the Greek word 'amphistomos' and eventually became the modern English word 'amphistomous'.

Initially, it meant 'having a mouth at both ends,' and this meaning has largely remained the same in modern usage.