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):

sinuous
    adj 1: curved or curving in and out; "wiggly lines" [syn:
           sinuate, sinuous, wiggly]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "sinuous":
   ambagious, anfractuous, bent, billowing, billowy, circuitous,
   circumlocutory, convoluted, convolutional, curvaceous, curvate,
   curvated, curve, curved, curvesome, curviform, curvilineal,
   curvilinear, curving, curvy, flexuose, flexuous, geosynclinal,
   incurvate, incurvated, incurved, incurving, involute, involuted,
   involutional, labyrinthine, mazy, meandering, meandrous, recurvate,
   recurvated, recurved, recurving, rivose, rivulose, roundabout,
   ruffled, serpentine, sinuate, sinuose, snake-shaped, snaky,
   torsional, tortile, tortuous, turning, twisted, twisting, twisty,
   undulant, wavy, whorled, winding, wreathlike, wreathy