'arrhythmia-suppressing' is a compound of 'arrhythmia' (from Greek elements 'a-' meaning 'without' + 'rhythmós' meaning 'rhythm', via New Latin) and 'suppressing' (from Latin 'supprimere' via Old French 'supprimer' and Middle English 'suppress'), where 'arrhythmia' originally denoted lack of rhythm and 'suppress' meant 'to press down'.

'arrhythmia' entered medical English from New Latin/Greek (Greek 'a-' + 'rhythmós'); 'suppress' evolved from Latin 'supprimere' → Old French 'supprimer' → Middle/Modern English 'suppress', and the present participle form became 'suppressing'. The two elements were later combined in modern medical English as a compound adjective.

Initially, 'arrhythmia' meant 'without rhythm' and 'suppress' meant 'to press down'; over time 'arrhythmia' narrowed to 'irregular heartbeat' and 'suppress' broadened to 'stop or reduce', so the compound came to mean 'reducing or preventing irregular heart rhythms'.