行为 (xíng wéi) is a noun meaning 'behavior' or 'conduct' — the way a person or animal acts in a given situation. The first character 行 means 'to go' or 'to carry out', and the second character 为 means 'to do' or 'to act'; together, they literally convey 'the doing' or 'the acting out' of something. This compound emphasizes observable actions rather than thoughts or intentions.

行为 is commonly used in psychology, education, ethics, and animal studies to describe patterns of action — for example, 'aggressive behavior', 'social behavior', or 'abnormal behavior'. It often appears in formal or academic contexts, though it’s also used in everyday speech when discussing someone’s conduct ('his behavior at the meeting was inappropriate'). Unlike more casual terms like 动作 (movement) or 举动 (gesture), 行为 carries a stronger implication of intentionality, consequence, or evaluation.