Improvement or enhancement, especially raising performance or quality of something.
農作物の品種改良によって収量が増えた。
Crop yields increased through variety improvements.
製品の改良を重ねて不良率を下げた。
We repeatedly improved the product and reduced the defect rate.
サービスの改良に顧客の意見を取り入れた。
We incorporated customer feedback into service improvements.