'unscheduled' originates from the prefix 'un-' meaning 'not' and the word 'schedule', which comes from the Latin word 'schedula', meaning 'a small slip of paper'.

'schedule' changed from the Old French word 'cedule' and eventually became the modern English word 'schedule'.

Initially, 'schedule' meant 'a small slip of paper', but over time it evolved into its current meaning of 'a plan for carrying out a process or procedure'.