'acherontic' originates from Greek, specifically the word 'Acheron,' which is a river in Greek mythology associated with the underworld.

'Acheron' was adopted into Latin as 'Acheron,' and eventually became the modern English word 'acherontic' through Middle English.

Initially, it referred to the river Acheron itself, but over time it evolved into its current meaning of relating to hellish or underworld conditions.