na-adjective
Used in formal or technical contexts to describe something that is not the main or principal element, such as a minor role, secondary factor, or non-essential item. Often appears in compound phrases like 非主要な要素 (minor element) or 非主要な役割 (secondary role).
この研究では非主要な要因は除外した。
In this study, we excluded minor factors.
彼は会議で非主要な役割しか与えられなかった。
He was given only a secondary role at the meeting.
副次的 also means 'secondary' or 'subsidiary', but is more common in everyday language, while 非主要 is more technical and formal.
Formed from the prefix 非- (non-) and 主要 (main/principal). The prefix 非- is a Sino-Japanese element meaning 'not' or 'non-', attached to nouns to form adjectival nouns.