'disunion' originates from the Latin prefix 'dis-' meaning 'apart' and the word 'union' meaning 'togetherness'.

'disunion' changed from the Old French word 'desunion' and eventually became the modern English word 'disunion'.

Initially, it meant 'the act of separating or dividing', but over time it evolved into its current meaning of 'the state of being disunited'.