'carcinogen' originates from New Latin and Greek, specifically the Greek word 'karkínos', where 'karkín-' meant 'crab' and the suffix '-gen' (from Greek 'genēs') meant 'born of, producing'.

'carcinogen' changed from the New Latin/modern scientific formation (e.g. 'carcinogenes' in New Latin/early scientific usage) and was adopted into English in the 19th century as the modern English word 'carcinogen'.

Initially it referred to something producing tumors (from Greek roots meaning 'crab' and 'producing'), and it has evolved into the current specific meaning: 'a substance or agent that can cause cancer'.