‘乙型肝炎’ (yǐ xíng gān yán) is the standard medical term for hepatitis B, a serious viral infection that affects the liver. The word breaks down as follows: ‘乙’ (yǐ) is the second character in the Chinese celestial stem system and here functions as a label—‘Type B’; ‘型’ (xíng) means ‘type’ or ‘form’; ‘肝’ (gān) means ‘liver’; and ‘炎’ (yán) means ‘inflammation’. Together, they literally mean ‘Type B liver inflammation’, reflecting both the causative virus (hepatitis B virus, HBV) and the organ it targets.

This term is used exclusively in clinical, public health, and scientific contexts in Chinese. It appears on medical reports, vaccination cards, health education materials, and official guidelines. Unlike informal terms like ‘乙肝’ (yǐ gān), which is widely used in daily speech, ‘乙型肝炎’ carries a formal, technical tone and is preferred in written documentation and professional communication. Awareness of this distinction helps learners choose appropriate register when discussing health topics.