in the dark

1. In a state of ignorance, uninformed, as in I was in the dark about their plans . This metaphor often appears in the locution keep someone in the dark , meaning “deliberately keep someone uninformed,” as in They kept me in the dark about their plans . [Late 1600s] For an antonym, see in the know .

2. In secret, in concealment, as in This agreement was concluded in the dark . [Early 1600s]