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bad; poor; inferior; defective
delinquent; hoodlum; hooligan
不良品は返品できます。
Defective products can be returned.
若い頃は不良だったと彼は言った。
He said he was a delinquent when he was young.
この製品には不良が多すぎると思う。
I think there are too many defects in this product.