'extremely' originates from the Latin word 'extremus,' which is the superlative of 'exter,' meaning 'outer.'

'extremus' transformed into the Old French word 'extreme,' and eventually became the modern English word 'extreme,' with 'extremely' as its adverbial form.

Initially, it meant 'outermost' or 'farthest,' but over time it evolved into its current meaning of 'to a very great degree.'