用済み

1. Origins, structure, and basic meaning

• Structure: The spelling is 用済み, read as ようずみ. It is a noun-like expression for something no longer needed because its intended use has already been completed.
• Basic usage: Modifying documents no longer needed appears in 用済みの書類, while discarding something as having served its purpose appears in 用済みとして捨てる.

2. Common pitfalls and similar expressions

• Difference from 不要
  • Unlike a general term for unnecessary, it includes the history that the item has already served its purpose.