The Collaborative International Dictionary of English v.0.48:

Principle \Prin"ci*ple\, v. t. [imp. & p. p. Principled; p.
   pr. & vb. n. Principling.]
   To equip with principles; to establish, or fix, in certain
   principles; to impress with any tenet, or rule of conduct,
   good or ill.
   [1913 Webster]

         Governors should be well principled.     --L'Estrange.
   [1913 Webster]

         Let an enthusiast be principled that he or his teacher
         is inspired.                             --Locke.
   [1913 Webster] Princock

WordNet (r) 3.0 (2006):

principled
    adj 1: based on or manifesting objectively defined standards of
           rightness or morality; "principled pragmatism and
           unprincipled expediency"; "a principled person" [ant:
           unprincipled]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "principled":
   Christian, blameless, clean, correct, creditable, decent, erect,
   estimable, ethical, fair, full of integrity, good, high-minded,
   high-principled, highly respectable, honest, honorable, immaculate,
   inviolate, irreproachable, just, law-abiding, law-loving,
   law-revering, manly, moral, moralistic, noble, proper, pure,
   reputable, respectable, right, right-minded, righteous, scrupulous,
   spotless, stainless, sterling, true-dealing, true-devoted,
   true-disposing, true-souled, true-spirited, truehearted,
   unblemished, uncorrupt, uncorrupted, undefiled, unimpeachable,
   unspotted, unstained, unsullied, untarnished, upright, uprighteous,
   upstanding, virtuous, worthy, yeomanly