診断

1. Origins, structure, and basic meaning

• Structure: 診断(しんだん) is assessing a condition to determine an illness or fault.
• Basic usage: It is used both for a doctor's assessment and for analyzing the cause of a machine failure.

2. Common pitfalls and similar expressions

• Examining versus assessing with 検査
  • 検査(けんさ) focuses on examining a condition or checking for abnormalities. 診断 focuses on assessing what the condition is, but a conclusion is not guaranteed, as the unsuccessful remote diagnosis in the example shows.