The Collaborative International Dictionary of English v.0.48:

Complicate \Com"pli*cate\, v. t. [imp. & p. p. Complicated; p.
   pr. & vb. n. Complicating.]
   To fold or twist together; to combine intricately; to make
   complex; to combine or associate so as to make intricate or
   difficult.
   [1913 Webster]

         Nor can his complicated sinews fail.     --Young.
   [1913 Webster]

         Avarice and luxury very often become one complicated
         principle of action.                     --Addison.
   [1913 Webster]

         When the disease is complicated with other diseases.
                                                  --Arbuthnot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

complicated
    adj 1: difficult to analyze or understand; "a complicated
           problem"; "complicated Middle East politics"

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "complicated":
   Byzantine, Daedalian, abstruse, arduous, balled up, beyond one,
   complex, compound, confounded, confused, convoluted, crabbed,
   cramp, daedal, devious, difficult, elaborate, embrangled,
   entangled, fancy, fouled up, garbled, gordian, hard,
   hard to understand, implicated, intricate, involuted, involved,
   jumbled, knotted, knotty, labyrinthian, labyrinthine, loused up,
   many-faceted, matted, mazy, meandering, messed up, mixed up,
   mucked up, multifarious, obfuscated, obscure, obscured, ornate,
   overtechnical, perplexed, ramified, recondite, roundabout,
   scrambled, screwed up, snarled, sophisticated, subtle, tangled,
   tangly, tough, twisted