The Collaborative International Dictionary of English v.0.48:

Sylphlike \Sylph"like`\, a.
   Like a sylph; airy; graceful.
   [1913 Webster]

         Sometimes a dance . . .
         Displayed some sylphlike figures in its maze. --Byron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sylphlike
    adj 1: moving and bending with ease [syn: lissome, lissom,
           lithe, lithesome, slender, supple, svelte,
           sylphlike]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "sylphlike":
   airy, attenuate, attenuated, boyish, delicate, diaphanous, diluted,
   elfin, elfish, elflike, ethereal, faery, fairy, fairyish,
   fairylike, fay, fine, fine-drawn, finespun, flimsy, frail, gauzy,
   girlish, gnomelike, gnomish, gossamer, gracile, insubstantial,
   lacy, light, misty, papery, pixieish, rare, rarefied, slender,
   slenderish, slight, slight-made, slim, slimmish, slinky, small,
   subtle, svelte, sylphidine, sylphine, sylphish, sylphy, tenuous,
   thin, thin-bodied, thin-set, thin-spun, thinnish, threadlike,
   vague, wasp-waisted, watered, watered-down, watery, weak, willowy,
   wiredrawn, wispy