undocumented

• 指没有官方记录或文件证明的；常用于法律或技术语境，如无证移民或未记录在案的事项。

Describes something that lacks official records or documentation; often used in legal or technical contexts.

1. Not recorded or registeredB2formal

   Not having official documents or records; lacking formal documentation.

   无证件的

   • The company had many undocumented expenses in its accounts.
   • Undocumented immigrants often face legal challenges.
   • The software contains undocumented features that users discovered.

   同义词unlistedunofficialunrecordedunregisteredunreported

   反义词documentedlistedrecordedregistered

2. Not supported by written evidenceB2formal

   Lacking written proof or official records to verify something.

   无书面证明的

   • The historian found undocumented claims in the old manuscript.
   • Many undocumented traditions were passed down orally.
   • The undocumented changes to the contract caused confusion.

   同义词unrecordedunregisteredunsubstantiatedunsupportedunverifiedunwritten

   反义词certifieddocumentedrecordedregistered