noun
Formal noun used in official or written contexts to state the reason or grounds for an action, decision, or situation. Often appears in phrases like 事由を説明する or 事由により.
欠席の事由を書面で提出してください。
Please submit the reason for your absence in writing.
やむを得ない事由により、会議は延
The meeting was postponed due to unavoidable circumstances.
Compound of 事 (thing, matter) and 由 (reason, cause). The combination has been used in formal Japanese to denote the reason or grounds for something.