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"