1. 机密的;不宜张扬的
    Something that is hush-hush is secret and not to be discussed with other people.

hush-hush的解释

    e.g. Apparently there''s a very hush-hush project under way up north...
           貌似这里往北的地方有个非常机密的项目正在进行。
    e.g. They were desperate to keep the marriage hush-hush.
           他们拼命想要瞒住这桩婚事。

1. conducted with or marked by hidden aims or methods

    e.g. clandestine intelligence operations
           cloak-and-dagger activities behind enemy lines
           hole-and-corner intrigue
           secret missions
           a secret agent
           secret sales of arms
           surreptitious mobilization of troops
           an undercover investigation
           underground resistance

    Synonym: clandestinecloak-and-daggerhole-and-corner(a)hugger-muggersecretsurreptitiousundercoverunderground