'southernmost' originates from Old English, specifically the word 'sūðerne,' where 'sūð' meant 'south' and '-ern' was a suffix indicating direction, combined with 'most' to indicate the furthest extent.

'sūðerne' transformed into the Middle English word 'southerne,' and eventually became the modern English word 'southernmost.'

Initially, it meant 'toward the south,' but over time it evolved into its current meaning of 'furthest to the south.'