reason

1. Origins, structure, and basic meaning

• Structure: 由 has 5 strokes, with the central vertical stroke extending above the box. It concerns reasons or routes through something.
• Basic usage: 理由 is read りゆう, and 経由 is read けいゆ.

2. Common pitfalls and similar expressions

• A reason and a route
  • The 由 in 理由 is read ゆう.
  • 欠席した理由 means the reason for an absence.
  • The 由 in 経由 is read ゆ.
  • 山の駅を経由して describes a travel route via a mountain station.
  • 担当者を経由して describes sending a document through the person in charge. 経由 can therefore identify an intermediary as well as a place.