Meaning & readings

empty, sky, void, vacant, vacuum

On’yomi クウ
Kun’yomi そら、あ.く、あ.き、あ.ける、から、す.く、す.かす、むな.しい
Nanori うつ、き、く

Origin

The character combines a hole or cavity (, the radical at the top) with the sound component below it. The hole radical makes sense for the meaning because an empty space or void is fundamentally an absence—a hollow area. The component doesn't add meaning; it's a sound hint that helped speakers remember roughly how to pronounce the character. Over time, the meaning expanded from "hole" or "empty space" to include the sky itself, since the sky appears as vast empty space above us.

AI-generated (claude-haiku-4-5), not yet reviewed. Formation type (automated guess): Phono-semantic (meaning + sound hint).

8 strokes

Components

  • radical top
  • sound hint bottom

A sound hint component points at the character’s pronunciation, not its meaning — don’t read a meaning into it.

Common words

  • 架空 かくう fictitious; imaginary
  • 虚空 こくう empty space; empty sky
  • 空間 くうかん space; room
  • 空気 くうき air; atmosphere
  • 空虚 くうきょ emptiness; hollowness
  • 空軍 くうぐん air force
  • 空港 くうこう airport
  • 空車 くうしゃ empty conveyance; empty taxi

Reference

Strokes
8
Kangxi radical
116
Grade
Grade 1 (Kyōiku)
Frequency rank
#304 (newspapers)
Former JLPT
level 4
Unicode
U+07A7A