空
1
emptiness;being empty
ほとんど空なのでガソリンを入れなくてはなりません。
I need to put some gas in the car, as it's almost empty.
2
prefix
not carrying anything;unburdened;empty-handed
3
prefix
dishonoured (bill, promise, etc.);false;no-show (reservation);put-on (cheeriness, courage, etc.);empty (compliments);insincere
Other forms
虚 【から】 (rarely used kanji form)