'diphtheria-causing' originates from Modern English, specifically by combining the disease name 'diphtheria' (ultimately from Greek 'diphthera') and the present-participial adjective-forming element '-causing' (from Latin 'causa' via Old French 'cause'), where 'diphthera' meant 'leather' and 'causa' meant 'reason' or 'cause'.

'diphtheria' entered English from Modern Latin 'diphtheria' in the 19th century, originally from Greek 'diphthera' meaning 'leather' (referring to the membrane); 'cause' comes from Old French 'cause' and Latin 'causa'. These elements were combined in modern English to form the descriptive compound 'diphtheria-causing'.

Initially, 'diphtheria' referred to the leather-like membrane observed in patients, but it later became the name of the disease; 'cause' has long meant 'that which produces an effect'. The compound now means 'producing or capable of producing diphtheria'.