Many kanji have multiple kun-yomi, but it’s hard to string those kun-yomi together in meaningful phrases, so enjoy 空の空 while you can! You can also see 空 standing alongside itself in certain compounds (though these repeated kanji might be represented as 空々 rather than 空空):
On the Funny Little Kanji 々… …
空空; 空々
When read as kūkū (with on-yomi), this compound means “empty,” “vacant,” or “void.” When read with kun-yomi, it becomes sorazora(shii), meaning “false, hypocritical.” (Next week we’ll see why sorazora(shii) has such a negative meaning.)
空々漠々 (kūkūbakubaku: vast, empty) empty + desert, wide
This archaic word uses the repetition kanji twice! The syllable ku appears four times in this compound. Try saying kūkūbakubaku aloud. Does it sound to you like a chant?! For some reason, I feel like I’m summoning a rooster!
空対空 (kūtaikū: air-to-air) air + opposite + air
This compound shows up as part of the term 空対空ミサイル (kūtaikū misairu: air-to-air missile).
