'acronycal' originates from Greek, specifically the word 'akronykhos,' where 'akro-' meant 'extreme' and 'nyx' meant 'night.'

'akronykhos' transformed into the Latin word 'acronychus,' and eventually became the modern English word 'acronycal.'

Initially, it meant 'related to the night,' but over time it evolved into its current meaning of 'relating to the setting of a star or planet at sunset.'