空
- empty, void, vacant;
- sky, space;
Etymology
It is a phono-semantic compound, composed of:
穴 (cave, opening) – semantic element, indicating hollowness, emptiness;
工 (gong, work, craft) – phonetic element, contributing sound.
The combined image originally suggested a hollow opening, an empty space, from which the meanings of emptiness, void, and sky developed.
Semantic range:
- empty, hollow, void – physical emptiness.
- sky, heavens, air – by extension, “open space above.”
- false, vain, insubstantial – metaphorical extension to “empty words, empty theories.”
- space, room, vacancy – as in 空間 (space), 空席 (vacant seat).
Usage in Korean
공간 (空間) – space
공군 (空軍) – air force
공기 (空氣 / 空器) – air; container
공복 (空腹) – empty stomach, fasting
공상 (空想) – daydream, fantasy
공석 (空席) – vacant seat
공중 (空中) – the air, midair
공지 (空地) – open lot, vacant land
공항 (空港) – airport
공허 (空虛) – emptiness, void
진공 (眞空) – vacuum
창공 (蒼空), 천공 (天空) – the sky, heavens
Even everyday expressions like 공책 (空冊, notebook = “empty book”) and 공언 (空言, empty words) use this character.
Additional notes
In Buddhism, 空 (kū / kong) is central to the doctrine of śūnyatā (emptiness, voidness), referring to the ultimate insubstantiality of all phenomena. This philosophical sense strongly influenced East Asian thought and vocabulary.