'宇航' (yǔ háng) is a compound noun meaning 'spaceflight' or 'space travel.' It combines two characters: 宇 (yǔ), short for 宇宙 (yǔzhòu, 'universe' or 'outer space'), and 航 (háng), from 航行 (hángxíng, 'to navigate' or 'to voyage'). Together, they literally mean 'navigation through outer space,' emphasizing human activity beyond Earth’s atmosphere — including manned missions, satellite launches, and interplanetary exploration.

This term is formal and technical, commonly used in news reports, scientific writing, and official contexts related to aerospace. It does not refer to aviation within Earth’s atmosphere (that’s 航空, hángkōng) nor to general astronomy (天文学, tiānwénxué). While often paired with words like 技术 (jìshù, 'technology'), 计划 (jìhuà, 'program'), or 员 (yuán, 'astronaut'), 宇航 itself functions as a standalone noun and rarely appears in casual speech.