太空
tàikōng · HSK 5
outer space
🚀 太 = supreme/great + 空 = empty/sky → the great emptiness = outer space
太 means extreme or vast (same character as in 太阳 sun), and 空 means empty or sky. Together they name the vast emptiness beyond the sky — outer space, the firmament.
太 — 大 'big' + extra dot 丶
太 originally derived from 大 ('big, person with arms outstretched') with an added stroke to mean 'greatest' or 'too much'. The extra dot intensifies 大, signaling something beyond merely big. Over time it came to mean 'very', 'too', or 'highest'.
空 — cave radical 穴 + 工 (phonetic)
Originally a phono-semantic compound: 穴 (cave, hole) gives the meaning of emptiness or hollow space, while 工 supplies the sound. The earliest sense was 'hole' or 'cavity,' which extended to 'empty,' 'sky,' and 'in vain.' The reading kòng (4th tone) specifically means 'free time' or 'vacancy.'