'logout' originates from the combination of 'log' and 'out', where 'log' refers to recording or entering data, and 'out' indicates exiting or leaving.

'log out' transformed into the noun 'logout' as computer systems became more prevalent, and the need for a term to describe the action of exiting a system arose.

Initially, it meant 'to exit a system', and this meaning has largely remained the same in modern usage.