‘太空’ (tài kōng) literally combines ‘太’ (tài), meaning ‘extreme’ or ‘great’, and ‘空’ (kōng), meaning ‘space’ or ‘emptiness’. Together, they refer to the vast, near-vacuum region beyond Earth’s atmosphere — what English speakers call ‘outer space’. It is a formal, standard term used in science, news, education, and official contexts, not in casual daily speech. Unlike the more poetic or literary ‘宇宙’ (yǔzhòu, ‘universe’) or the technical ‘外层空间’ (wàicéng kōngjiān, ‘outer space’), ‘太空’ emphasizes the physical expanse surrounding Earth and is often associated with space exploration, satellites, and astronauts.

The word appears frequently in compound terms like ‘太空人’ (tàikōng rén, astronaut), ‘太空站’ (tàikōng zhàn, space station), and ‘太空船’ (tàikōng chuán, spacecraft). It carries a sense of human achievement and scientific endeavor — for example, China’s Tiangong space station is routinely described as operating in ‘太空’. While it can occasionally appear in metaphorical expressions, its core meaning remains strictly astronomical and geographic.