Word: 真空 (zhēnkōng) 真空 dictionary entry zhēnkōng vacuum; vacuum; to not wear underwear Full dictionary entry for 真空 Example sentences using 真空 2 sentences, showing page 1 of 1. 太空里是真空，没有声音。 Tàikōng lǐ shì zhēnkōng, méiyǒu shēngyīn. Space is a vacuum, so there is no sound. 月球表面几乎是真空。 Yuèqiú biǎomiàn jīhū shì zhēnkōng. The surface of the moon is almost a vacuum.