阳刚之气 (yáng gāng zhī qì) is a set phrase meaning 'manliness' or 'masculine spirit,' rooted in traditional Chinese yin-yang philosophy where 阳 (yáng) represents the male, active, firm principle. It describes the quality of being virile, strong, and courageous, often contrasted with effeminate traits. In modern Chinese, it appears frequently in discussions about gender roles and the cultivation of masculine virtues.