'cardiodepressant' originates from a combination of the Greek prefix 'cardio-' (from Greek 'kardia') and the Late Latin/English element 'depressant' (from Latin 'deprimere'), where 'kardia' meant 'heart' and 'deprimere' meant 'to press down'.

'depressant' developed from Latin 'deprimere' ('de-' + 'primere' = 'to press down') into Late Latin/Old French forms and entered English as 'depress'/'depressant'; the combining form 'cardio-' (from Greek 'kardia') was attached in modern medical English to create the compound 'cardiodepressant'.

Initially, 'depressant' literally implied 'that which presses down'; over time it came to mean 'an agent that reduces physiological or mental activity', and in the compound 'cardiodepressant' it specifically denotes reduction of heart activity.