The Collaborative International Dictionary of English v.0.48:

Gently \Gen"tly\, adv.
   In a gentle manner.
   [1913 Webster]

         My mistress gently chides the fault I made. --Dryden.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gently
    adv 1: in a gradual manner; "a gently sloping terrain"
    2: in a gentle manner; "he talked gently to the injured animal"
       [syn: gently, mildly]
    3: with little weight or force; "she kissed him lightly on the
       forehead" [syn: lightly, softly, gently]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "gently":
   a la sourdine, cautiously, circumspectly, compliantly, crawlingly,
   creepingly, deliberately, delicately, dilatorily, dimly, easily,
   faintly, falteringly, feebly, haltingly, hushedly, idly,
   in low gear, in march time, in slow motion, in slow tempo,
   indolently, languidly, languorously, leisurely, like a lamb,
   limpingly, lingeringly, loiteringly, low, meekly, mildly,
   moderately, pacifically, peaceably, pianissimo, piano, pokily,
   pokingly, quietly, relaxedly, reluctantly, slow, slowly,
   sluggishly, softly, sordamente, sordo, subduedly, submissively,
   tamely, tarryingly, tenderly, tentatively, under easy sail,
   unhurriedly, weakly, with agonizing slowness, with deliberation