confidential
adj. 机密的，保密的；（言谈举止）神秘的，隐秘的；受信任的，委以机密的
例句
My letter is, of course, strictly private and confidential.
当然，我的信纯属私人信件，务须保密。
《牛津词典》
The deliberations of the committee are completely confidential.
委员会的审议过程是绝对保密的。
From time to time he passed on confidential information to him.
他不时地传送机密情报给他。
《柯林斯英汉双解大词典》
