天空
tiānkōng · HSK 3
sky
☁️ 天 = sky/heaven + 空 = empty/void — the empty heavens above
天 depicts a person 大 with a flat line above marking what is overhead. 空 combines 穴 (cave/hole) with 工 (phonetic) for emptiness. Together: the vast empty expanse overhead — the sky.
天 — 一 (one/sky) above 大 (big person)
Originally a pictograph of a person (大) with an emphasized head, representing what is above — the sky or heavens. The top stroke evolved into 一, symbolizing the vast expanse overhead. From 'sky' it extended to mean 'day,' 'heaven,' and 'nature.'
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.'