親しん展てん書しょ

noun

confidential letter

A letter marked as confidential, intended only for the named recipient. Often used in formal or business correspondence.

• この封ふう筒とうには「親しん展てん書しょ」と書かいてある。

  This envelope is marked 'confidential letter'.

• 親しん展てん書しょは本ほん人にん以い外がいが開かい封ふうしてはいけない。

  A confidential letter must not be opened by anyone other than the addressee.