回应 means 'to respond' or 'to reply', and is commonly used in both spoken and written Chinese to describe a reaction—verbal, written, or even behavioral—to something said, asked, or done. The first character 回 (huí) literally means 'to return' or 'to go back', suggesting the idea of sending something back; the second character 应 (yìng) means 'to answer' or 'to comply', often implying readiness or appropriateness. Together, they convey the sense of giving a timely, relevant reply or reaction.

This verb is neutral in register and widely used in daily communication—such as replying to messages, reacting to questions in meetings, or acknowledging feedback. It can take objects (e.g., 回应问题, 回应邀请), and often appears with aspect particles like 了 or 过. While it overlaps with 回答 (to answer), 回应 emphasizes the act of responding *in reaction to* something specific—not just providing information—and may include non-verbal responses like nodding or smiling when appropriate.