NDA       
noun [ C ] uk/ˌen.diːˈeɪ/ us/ˌen.diːˈeɪ/
 保密协议(non-disclosure agreement的缩写)
abbreviation for non-disclosure agreement: a legal document stating that someone will not tell anyone certain private information, especially about the company they work for
  I think it's smart that she's had employees sign NDAs. 我觉得她让雇员签署保密协议是明智的做法。 
 Never provide confidential information without an NDA. 如果要提供机密信息,一定要先签署保密协议。 
 - More examples
- They didn't make any of us sign an NDA or anything.
- I am unable to deliver a full-blown project summary until we have signed an NDA.
- NDAs are signed legal agreements between you and those you show your invention to, to prevent them from manufacturing your invention or telling others about it.