'outside' originates from Middle English, specifically the combination of 'out' and 'side', where 'out' meant 'beyond' and 'side' referred to 'surface'.

'outside' changed from the Old English word 'ūtsīde' and eventually became the modern English word 'outside'.

Initially, it meant 'the outer surface', but over time it evolved into its current meaning of 'beyond the confines'.