1.
secretiveness; secretive nature; tendency to keep things private
A personal trait or habitual attitude of keeping information, feelings, or plans hidden from others.
2.
policy of secrecy; principle of confidentiality
An organizational or institutional approach that prioritizes withholding information from the public or outsiders.
Composed of 秘密 (secret) + 主義 (-ism; principle). When describing a person, it characterizes someone who habitually keeps things to themselves and doesn't share personal information easily. When describing an organization, it refers to a deliberate policy of restricting information.