残留

1. Origins, structure, and basic meaning

• Structure: 残留, read ざんりゅう, denotes material or a state that remains after cleaning or another process.
• Basic usage: It covers preventing detergent from remaining in a container and testing substances left in food.

2. Common pitfalls and similar expressions

• Material remaining after a process
  • The focus is material left after cleaning or processing, not every component originally present.