COVERTLY
Meaning of COVERTLY in English
adverb
Synonyms: secretly , by stealth, clandestinely, furtively, hugger-mugger, in camera, privately, stealthily, sub rosa, surreptitiously
Merriam Webster.
Collegiate thesaurus English vocabulary.
Английский энциклопедический словарь тезаурус.
2003