BEHIND SOMEONE'S BACK
Meaning of BEHIND SOMEONE'S BACK in English
SECRETLY, without someone's knowledge, on the sly, slyly, sneakily, covertly, surreptitiously, furtively.
2192; headword
Concise Oxford thesaurus English vocabulary.
Краткий оксфордский словарь английского языка тезаурус.
2012