'unemotional' originates from the prefix 'un-' meaning 'not' and the word 'emotional', which comes from the Latin 'emotio', meaning 'a moving, stirring'.

'emotio' transformed into the French word 'émotion', and eventually became the modern English word 'emotion', with 'un-' added to form 'unemotional'.

Initially, it meant 'not moved or stirred', but over time it evolved into its current meaning of 'not showing or feeling emotions'.