confidentially Synonyms

between us on the qt on the q.t. off the record in confidence in camera surreptitiously secretively discreetly conspiratorially collusively clandestinely between ourselves behind someone's back on the quiet on the side on the sly unofficially unobtrusively unobserved under the counter under cover unconstitutionally unbeknownst unattainably trustfully thievishly undercover sneakingly sneakily behind closed doors in private in secret ourselves inwardly intimately informally indoors hiddenly furtively familiarly esoterically covertly confidential confidence closely parentally personally private mystically