不可

ふか

wrong, bad, improper, unjustifiable, inadvisable

JLPT N3

Details

Part of Speech:: Noun which may take the genitive case particle 'no', Na-adjective , Noun, Noun, used as a suffix
Romaji:: fuka

この方法は不可です。

This method is wrong.

あれは不可なやつだ

Those are bad guys.