真空
しんくう · shinkuu · JLPT N2 · noun
vacuum
🌌 shin (new/true) + kuu (sky/empty): a true empty space, like the void of outer space
真 means true or genuine, 空 means empty or sky. Together they name a truly empty space with no air, like the vacuum of outer space.
真 — 匕 (spoon) over 目 (eye) over 八 (eight/base)
真 originally depicted a person or vessel used in ritual, conveying the idea of something genuine or true. Over time the form was reanalyzed as components like 匕, 目, and a base, but the core meaning of 'real, true, genuine' has remained stable since early bronze inscriptions.
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.'