轻信 is a verb meaning 'to believe too readily' or 'to be gullible'—that is, accepting information as true without sufficient evidence or critical evaluation. The character 轻 (qīng) means 'light' or 'casual', suggesting lack of seriousness or depth, while 信 (xìn) means 'to believe' or 'trust'. Together, they convey the idea of believing in a superficial, unexamined way—like treating trust as something weightless and effortless. This word carries a negative connotation and often implies vulnerability to deception or manipulation.

It’s commonly used in contexts warning against uncritical acceptance—such as online rumors, persuasive advertising, or overly flattering statements from strangers. While not formal or literary, it appears frequently in news commentary, educational materials, and everyday advice about media literacy and personal judgment. It’s typically followed by an object (e.g., 轻信谣言, 轻信他人), and rarely stands alone without context.