Synonyms of secretly

2 Syllables
slyly, quietly, hush-hush
3 Syllables
stealthily, privily, craftily, covertly, shiftily, dingily, duskily, sneakily, inwardly, hazily
4 Syllables
insidiously, furtively, privately, unobserved, invisibly, familiarly, obscurely, nebulously, tenebrously, personally
5 Syllables
surreptitiously, inconspicuously, confidentially, clandestinely, indefinably, intimately, unofficially, underhandedly
6 Syllables
conservatively, unobtrusively