root cause

Noun

idiomatic

(idiomatic) An initiating cause of a chain of events which leads to an outcome or effect of interest.

Japanese Meaning

一連の出来事の発端となる原因、すなわち事象の連鎖を引き起こす根本的な原因

Before we design a solution, it's crucial to identify the root cause of the recurring server outages.

解決策を設計する前に、繰り返し発生するサーバー障害の根本原因を特定することが重要です。

Sense（1）

(idiomatic) An initiating cause of a chain of events which leads to an outcome or effect of interest.

However, the report finds that the "root cause has not yet been established".

root causes

（ plural ）