退屈

1. Origins, structure, and basic meaning

• Structure: 退屈 (たいくつ) denotes boredom and forms expressions for being bored or finding something tedious.
• Basic usage: 退屈していた describes a person's continuing boredom; 退屈しない denies becoming bored when a book is available.

2. Common pitfalls and similar expressions

• A bored person and a non-tedious situation
  • The first context describes the experiencer as bored; the second says the wait does not produce boredom. English adjective choice follows that focus.