na-adjective, noun
impure; adulterated; dishonest
Describes substances that are not pure, motives that are not sincere, or actions that are underhanded. Often used in compounds like 不純物 (impurity) or 不純異性交遊 (inappropriate heterosexual relationships).
この水は不純物が多くて飲めない。
This water contains too many impurities and cannot be drunk.
彼の動機は不
I think his motives are impure.