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Meanings

emptiness, being empty, not carrying anything, unburdened, empty-handed, dishonoured (bill, promise, etc.), false, no-show (reservation), put-on (cheeriness, courage, etc.), empty (compliments), insincere

Readings

くう、あく、あける、から、そら、あな、うつける、うつろ、うろ、すく、むなしい

The bundled data does not distinguish on’yomi from kun’yomi, so readings are listed together.