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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
「空」 has other readings with different meanings.
箱の中が空っぽだった。
The box was completely empty.
財布が空になってしまったよ。
My wallet has become empty.
空っぽの部屋に一人で立っていると寂しい。
Standing alone in an empty room feels lonely.