空中
kōngzhōng · HSK 5
in the air
☁️✈️ 空 (empty) + 中 (middle) = the empty middle = up in the air
空 means empty/sky and 中 means middle/inside. Together 空中 literally reads as the empty middle space — the open expanse overhead where birds and planes travel. Common in phrases like 空中飞行 (flying in the air).
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.'
中 — vertical stroke 丨 through enclosure 口
Pictograph of a banner or pole piercing the center of a target or territory, depicting the idea of 'middle' or 'center'. The horizontal frame represents boundaries, and the vertical line marks the central axis. The meaning extended from spatial center to 'middle, central, China' (中国, the Middle Kingdom).