異例

1. Origins, structure, and basic meaning

• Structure: 異例, read いれい, describes a departure from usual cases or practice.
• Basic usage: 新人が代表に選ばれるのは異例だった。 says it was unusual for a newcomer to be chosen as representative.

2. Common pitfalls and similar expressions

• Modifying a noun
  • Use の before a noun, as in 異例の長さ; predicate forms include 異例だ and 異例だった.
• Exception and evaluation
  • 異例 focuses on departure from usual practice. It can describe a long meeting, as in 異例の長さ, so it does not always express praise.