'laxative' originates from Latin, specifically the Medieval Latin word 'laxativus', where the root 'laxare' meant 'to loosen'.

'laxative' changed from Medieval Latin 'laxativus' (from Latin 'laxare') into English via Late Latin/Medieval Latin usage and became the modern English word 'laxative'.

Initially, it meant 'causing loosening', especially of the bowels, and over time it has remained largely the same in medical and general usage as 'a substance that loosens the bowels' or 'having that effect'.