Synonyms of simply

2 Syllables
subtly, thinly, lightly, hardly, faintly, scantly, frankly, quietly, humbly
3 Syllables
flippantly, leniently, tenuously, timidly, candidly, thoughtlessly, openly, solely, chastely, bashfully, directly, brazenly, flagrantly, honestly, forthrightly, wantonly, abjectly, commonly, sparsely, heedlessly, slightingly, airily, breezily, daintily, merely, artlessly, easily, modestly, sparingly
4 Syllables
ethereally, frivolously, demurely, rigorously, uniquely, unerringly, informally, ingloriously, detectably, naturally, agilely, guilelessly, ingenuously, sincerely, straightforwardly, literally
5 Syllables
indisputably, undisputably, undividedly, unsubstantially, undeviatingly, unabashedly, unashamedly, submissively, ordinarily, intelligibly, matter-of-factly, unaffectedly, unpretentiously
6 Syllables
unhesitatingly, uncomplicatedly
7 Syllables
characteristically, apologetically