‘反面’ literally combines ‘反’ (fǎn), meaning ‘opposite’ or ‘reverse’, and ‘面’ (miàn), meaning ‘side’ or ‘surface’. Together, it refers to the back or reverse side of a physical object — for example, the side of a coin opposite the ‘heads’ side, or the underside of a piece of paper. This is its most concrete, everyday usage.

Figuratively, ‘反面’ also denotes the negative or undesirable aspect of something — such as the ‘downside’ of a policy, the ‘dark side’ of technology, or the ‘unfavorable consequences’ of an action. In this sense, it’s often paired with ‘正面’ (zhèngmiàn, ‘positive side’) to form a contrastive pair. It’s commonly used in discussions of ethics, social issues, and critical analysis, and appears frequently in news reports, essays, and classroom debates.