主しゅ要よう因いん

noun

primary factor; main cause

Used in analytical or explanatory contexts to identify the most important reason or element behind a situation. Often contrasted with 副因 (secondary factor).

See also: 要因

• 事じ故この主しゅ要よう因いんはスピードの出だし過すぎだった。

  The primary factor in the accident was excessive speed.

• この問もん題だいの主しゅ要よう因いんを特とく定ていする必ひつ要ようがある。

  We need to identify the main cause of this problem.