underhandedly Synonyms

underhand unscrupulously underarm untruthfully mendaciously unfairly sub-rosa underhanded stealthily clandestinely deviously dishonorably treacherously sneakily shiftily on the sly on the quiet insidiously in camera surreptitiously slyly slily disloyally dishonestly deceptively deceitfully crookedly craftily covertly corruptly falsely fraudulently furtively shadily secretly quietly privately overly intimately insincerely immorally confidentially