be not to know

English

Verb

be not to know (third-person singular simple present is not to know, present participle being not to know, simple past was not to know, past participle been not to know)

1. (UK, especially in the past) To not have the required information.

   You weren’t to know. ― You couldn’t have known.

2. Used other than figuratively or idiomatically: see be,‎ not,‎ to,‎ know.

Further reading

• “be not to know” in Longman Dictionary of Contemporary English, Longman.
• “be not to know”, in OneLook Dictionary Search.