副産物

1. Origins, structure, and basic meaning

• Structure: Written 副産物 and read ふくさんぶつ, it is a secondary result produced alongside the main output of a process or activity.
• Basic usage: It covers wood-processing material reused as fuel and an unexpected result emerging from research.

2. Common pitfalls and similar expressions

• Not necessarily waste
  • A by-product is secondary, but it may still be useful or valuable.