The Collaborative International Dictionary of English v.0.48:

Sinuous \Sin"u*ous\, a. [L. sinuosus, fr. sinus a bent surface,
   a curve: cf. F. sinueux. See Sinus.]
   Bending in and out; of a serpentine or undulating form;
   winding; crooked. -- Sin"u*ous*ly, adv.
   [1913 Webster]

         Streaking the ground with sinuous trace. --Milton.
   [1913 Webster]

         Gardens bright with sinuous rills.       --Coleridge.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sinuously
    adv 1: in a sinuous manner