The phrase "letting it be known" implies an action of making something public or openly communicating a particular piece of information. Antonyms to this phrase would be language that too suggests concealment, secrecy, or withholding information. Examples of such phrases are keeping mum, silence, hush-hush, non-disclosure, holding back, or not revealing. The opposite of "letting it be known" indicates keeping something to oneself or intentionally not disclosing a particular fact. The choice of language can influence how information is conveyed and how information recipients perceive the communication. Therefore, it is essential to choose the right phrase for the message to be accurately and adequately conveyed.