極秘

1. Origins, structure, and basic meaning

• Structure: 極秘 is read as ごくひ and is a noun and na-adjectival expression for information kept top secret or strictly confidential.
• Basic usage: Discovering top-secret material appears in 極秘資料を見つける, while keeping a plan confidential until announcement appears in 計画を極秘にする.

2. Common pitfalls and similar expressions

• Noun modification and imposed status
  • Use the compound 極秘資料 before a noun and 極秘にする for making or keeping something confidential.
• Difference from 秘密
  • Unlike the broad word for a secret, this term marks information under an especially strict level of nondisclosure.