'astronomically' originates from the Greek word 'astronomikos', where 'astron' meant 'star' and 'nomos' meant 'law'.

'astronomikos' transformed into the Latin word 'astronomicus', and eventually became the modern English word 'astronomical' through Middle English.

Initially, it meant 'pertaining to the laws of the stars', but over time it evolved into its current meaning of 'extremely large or vast'.