[syn: tortuous, twisting, twisty, winding, voluminous]
3.  not straightforward; 
- Example: "his tortuous reasoning"
The Collaborative International Dictionary of English v.0.48:
Tortuous \Tor"tu*ous\, a. [OE. tortuos, L. tortuosus, fr. tortus
   a twisting, winding, fr. torquere, tortum, to twist: cf. F.
   tortueux. See Torture.]
   1. Bent in different directions; wreathed; twisted; winding;
      as, a tortuous train; a tortuous leaf or corolla.
      [1913 Webster]
            The badger made his dark and tortuous hole on the
            side of every hill where the copsewood grew thick.
                                                  --Macaulay.
      [1913 Webster]
   2. Fig.: Deviating from rectitude; indirect; erroneous;
      deceitful.
      [1913 Webster]
            That course became somewhat lesstortuous, when the
            battle of the Boyne had cowed the spirit of the
            Jakobites.                            --Macaulay.
      [1913 Webster]
   3. Injurious: tortious. [Obs.]
      [1913 Webster]
   4. (Astrol.) Oblique; -- applied to the six signs of the
      zodiac (from Capricorn to Gemini) which ascend most
      rapidly and obliquely. [Obs.] --Skeat.
      [1913 Webster]
            Infortunate ascendent tortuous.       --Chaucer.
      [1913 Webster] --Tor"tu*ous*ly, adv. --
      Tor"tu*ous*ness, n.
      [1913 Webster]
WordNet (r) 3.0 (2006):
tortuous
    adj 1: highly complex or intricate and occasionally devious;
           "the Byzantine tax structure"; "Byzantine methods for
           holding on to his chairmanship"; "convoluted legal
           language"; "convoluted reasoning"; "the plot was too
           involved"; "a knotty problem"; "got his way by
           labyrinthine maneuvering"; "Oh, what a tangled web we
           weave"- Sir Walter Scott; "tortuous legal procedures";
           "tortuous negotiations lasting for months" [syn:
           Byzantine, convoluted, involved, knotty,
           tangled, tortuous]
    2: marked by repeated turns and bends; "a tortuous road up the
       mountain"; "winding roads are full of surprises"; "had to
       steer the car down a twisty track" [syn: tortuous,
       twisting, twisty, winding, voluminous]
    3: not straightforward; "his tortuous reasoning"
Moby Thesaurus II by Grady Ward, 1.0:
139 Moby Thesaurus words for "tortuous":
   Gongoresque, Johnsonian, affected, ambagious, ambiguous,
   anamorphous, anfractuous, askew, asymmetric, bedizened, bent,
   big-sounding, billowing, billowy, bowed, circuitous,
   circumlocutory, cockeyed, complicated, contorted, convoluted,
   convolutional, cranky, crazy, crooked, crumpled, crunched, curled,
   curling, curvaceous, curvate, curvated, curve, curved, curvesome,
   curviform, curvilineal, curvilinear, curving, curvy, deceptive,
   declamatory, deviative, devious, distorted, elevated, euphuistic,
   flamboyant, flaming, flashy, flaunting, flexuose, flexuous,
   fulsome, garish, gaudy, geosynclinal, grandiloquent, grandiose,
   grandisonant, high-flowing, high-flown, high-flying, high-sounding,
   highfalutin, incurvate, incurvated, incurved, incurving, indirect,
   inkhorn, intricate, involute, involuted, involutional, involved,
   irregular, labyrinthine, lexiphanic, lofty, lopsided, lurid,
   magniloquent, mazy, meandering, meandrous, meretricious,
   misleading, nonsymmetric, one-sided, orotund, ostentatious,
   overdone, overelaborate, overinvolved, overwrought, pedantic,
   pompous, pretentious, recurvate, recurvated, recurved, recurving,
   rhetorical, rivose, rivulose, roundabout, ruffled, sensational,
   sensationalistic, sententious, serpentine, showy, sinuate, sinuose,
   sinuous, snaky, sonorous, sprung, stilted, tall, torsional,
   tortile, tricky, turning, twisted, twisting, twisty, undulant,
   unstraightforward, unsymmetric, wandering, warped, wavy, whorled,
   winding, wreathlike, wreathy, zigzag