防疫 (fáng yì) literally means 'to prevent epidemics' — 防 (fáng) means 'to guard against, prevent', and 疫 (yì) refers to 'epidemic, infectious disease'. Together, they form a compound noun meaning 'epidemic prevention' or 'disease control measures'. It is commonly used in public health contexts to describe actions taken by governments, hospitals, or individuals to stop the spread of contagious illnesses — such as vaccination campaigns, border health checks, mask mandates, or hygiene education.

The term carries formal, institutional weight and appears frequently in official announcements, news reports, and health guidelines. While it can refer to both proactive measures (e.g., vaccines) and reactive ones (e.g., quarantine), it emphasizes collective, organized efforts rather than personal health habits alone. It is not used for non-infectious conditions like diabetes or cancer — those fall under broader terms like 'health care' (医疗) or 'disease prevention' (疾病预防).