無駄

1. Origins, structure, and basic meaning

• Structure: 無駄, read むだ, means waste or something that fails to serve a useful purpose despite the resources spent.
• Basic usage: It describes leaving water running, while the negated phrase 無駄にはならない says that an experience will not be wasted.

2. Common pitfalls and similar expressions

• Waste and the negated sense of not being in vain
  • It describes waste, such as leaving water running, but in a negative construction it means that practice was not in vain. Missing the negation reverses the meaning.