The Collaborative International Dictionary of English v.0.48:

Consider \Con*sid"er\ (k[o^]n*s[i^]d"[~e]r), v. t. [imp. & p. p.
   Considered (k[o^]n*s[i^]d"[~e]rd); p. pr. & vb. n.
   Considering.] [F. consid['e]rer, L. considerare,
   -sideratum, to consider, view attentively, prob. fr. con- +
   sidus, sideris, star, constellation; orig., therefore, to
   look at the stars. See Sidereal, and cf. Desire.]
   1. To fix the mind on, with a view to a careful examination;
      to think on with care; to ponder; to study; to meditate
      on.
      [1913 Webster]

            I will consider thy testimonies.      --Ps. cxix.
                                                  95.
      [1913 Webster]

            Thenceforth to speculations high or deep
            I turned my thoughts, and with capacious mind
            Considered all things visible.        --Milton.
      [1913 Webster]

   2. To look at attentively; to observe; to examine.
      [1913 Webster]

            She considereth a field, and buyeth it. --Prov.
                                                  xxxi. 16.
      [1913 Webster]

   3. To have regard to; to take into view or account; to pay
      due attention to; to respect.
      [1913 Webster]

            Consider, sir, the chance of war: the day
            Was yours by accident.                --Shak.
      [1913 Webster]

            England could grow into a posture of being more
            united at home, and more considered abroad. --Sir W.
                                                  Temple.
      [1913 Webster]

   4. To estimate; to think; to regard; to view.
      [1913 Webster]

            Considered as plays, his works are absurd.
                                                  --Macaulay.
      [1913 Webster]

   Note: The proper sense of consider is often blended with an
         idea of the result of considering; as, "Blessed is he
         that considereth the poor." --Ps. xli. 1.; i.e.,
         considers with sympathy and pity. "Which [services] if
         I have not enough considered." --Shak.; i.e., requited
         as the sufficient considering of them would suggest.
         "Consider him liberally." --J. Hooker.

   Syn: To ponder; weigh; revolve; study; reflect or meditate
        on; contemplate; examine. See Ponder.
        [1913 Webster]

WordNet (r) 3.0 (2006):

considered
    adj 1: carefully weighed; "a considered opinion"

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "considered":
   advised, aforethought, aimed, aimed at, calculated, conscious,
   contemplated, deliberate, deliberated, designed, envisaged,
   envisioned, intended, intentional, knowing, meant, meditated,
   of design, planned, premeditated, prepense, projected, proposed,
   purposed, purposeful, purposive, reasoned, studied, studious,
   teleological, thought-out, voluntary, weighed, willful, witting