'outdoor' originates from the combination of 'out' and 'door', where 'out' meant 'outside' and 'door' referred to an entrance or exit.

'outdoor' evolved from the Old English 'ūt' (out) and 'duru' (door), eventually forming the modern English word 'outdoor'.

Initially, it meant 'outside the door', but over time it evolved into its current meaning of 'situated or occurring outside'.