na-adjective
Describes something that is not primary or main, often used in contrast with 一次的 (primary). Common in technical, academic, or formal contexts.
この問題は二次的なものだ。
This issue is secondary.
二次的な原因を調査する必要がある。
We need to investigate secondary causes.
副次的 also means 'secondary' or 'subsidiary', but often implies something incidental or accompanying, whereas 二次的 is more neutral and often used in systematic or hierarchical contexts.
Compound of 二次 (にじ, 'secondary') + 的 (てき, '-like, -al'). 二次 is itself from 二 (に, 'two') + 次 (じ, 'order, next').