'inarticulacy' originates from Latin, specifically the word 'inarticulatus,' where 'in-' meant 'not' and 'articulatus' meant 'distinctly spoken.'

'inarticulatus' transformed into the Medieval Latin word 'inarticulatus,' and eventually became the modern English word 'inarticulacy.'

Initially, it meant 'not distinctly spoken,' but over time it evolved into its current meaning of 'inability to express oneself clearly.'