The Collaborative International Dictionary of English v.0.48:

Premeditate \Pre*med"i*tate\, v. t. [imp. & p. p. Premeditated
   (-t[=a]`t?d); p. pr. & vb. n. Premeditating.] [L.
   praemeditatus, p. p. of praemeditari; prae before + meditari
   to meditate. See Meditate.]
   To think on, and revolve in the mind, beforehand; to contrive
   and design previously; as, to premeditate robbery.
   [1913 Webster]

         With words premeditated thus he said.    --Dryden.
   [1913 Webster]

WordNet (r) 3.0 (2006):

premeditated
    adj 1: characterized by deliberate purpose and some degree of
           planning; "a premeditated crime" [ant: unpremeditated]

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "premeditated":
   advised, aforethought, calculated, conscious, considered,
   contrived, cooked-up, cut out, cut-and-dried, cut-and-dry,
   deliberate, designed, fixed, in the bag, intended, intentional,
   on ice, packed, planned, plotted, prearranged, preconceived,
   preconcerted, preconsidered, precontrived, predeliberated,
   predetermined, preordered, prepense, preresolved, purposive,
   put-up, rigged, schemed, set-up, stacked, studied, studious,
   thought-out