The phrase "in concealment" refers to the act of hiding or keeping something hidden from others. Synonyms for this phrase could include "in secrecy," "covertly," "furtively," "clandestinely," "surreptitiously," "privately," or "behind closed doors." Each of these words conveys a sense of secrecy and hiding, suggesting that something is being kept from view or disguised from others. Whether it's a hidden agenda, a secret relationship, or private thoughts, these phrases all capture the idea of something being hidden away from prying eyes or curious observers. By using these synonyms, we can add nuance and complexity to our language and more effectively communicate our ideas.