挺胸 (tǐng xiōng) literally means 'to straighten the chest' and describes the physical action of drawing the chest forward and upward, often to appear more confident, alert, or disciplined. The character 挺 conveys 'to extend', 'to straighten', or 'to push out', while 胸 means 'chest' or 'thorax'. Together, they form a compound verb emphasizing upright posture.

This term is commonly used in contexts related to physical health, military training, martial arts, dance, and public speaking — anywhere posture matters. It’s not just about appearance; in traditional Chinese medicine and fitness, 挺胸 is associated with proper breathing, spinal alignment, and energetic presence. However, overdoing it can cause strain, so balanced posture (with relaxed shoulders and natural curvature of the spine) is encouraged. It’s rarely used metaphorically on its own but may appear in idioms like 挺胸抬头 (tǐng xiōng táng tóu, 'puff out chest and lift head'), expressing bold confidence.