noun
blank lottery ticket; losing ticket
Refers to a lottery ticket that did not win a prize. Often used in the context of 宝くじ (lottery).
宝くじを買ったけど、全部空くじだった。
I bought lottery tickets, but they were all blanks.
抽選の結果、空くじを引いてしまった。
As a result of the drawing, I drew a losing ticket.
Compound of 空 (から, 'empty') and くじ ('lottery ticket').