'cardiotonic' originates from Modern Latin, specifically the word 'cardiotonicus', where the Greek prefix 'cardio-' (from 'kardia') meant 'heart' and the Greek root 'tonic' (from 'tonos') meant 'tension' or 'stretching'.

'cardiotonic' changed from New/Modern Latin 'cardiotonicus' (formed from Greek elements) and entered English in the 19th century as the medical term 'cardiotonic'.

Initially it meant 'relating to or strengthening the tension/power of the heart', and over time it became specifically used for 'a substance that increases the force of heart contractions' or 'having such an effect'.