noun
without studying; not having studied
Slang noun used mainly by students to describe taking a test or exam without any preparation. Often used in phrases like 無勉で受ける (take without studying).
明日のテスト、無勉で受けるしかない。
I have no choice but to take tomorrow's test without studying.
無勉だったけど、意外とできた。
I didn't study, but I did surprisingly well.