腐らせる

1. Origins, structure, and basic meaning

• Structure: 腐らせる(くさらせる) is the causative form of 腐る(くさる) and means causing or allowing something to rot or spoil.
• Basic usage: It describes someone letting fruit spoil by forgetting to store it, or poor conditions causing roots to rot.

2. Common pitfalls and similar expressions

• A change and its cause
  • 果物が腐る describes fruit rotting; 果物を腐らせる focuses on causing or allowing that change.
• Intention and result
  • In the example, 腐らせてしまった means unintentionally letting the fruit spoil after forgetting to store it. It is not limited to deliberately causing rot.