The Collaborative International Dictionary of English v.0.48:

Knowingly \Know"ing*ly\, adv.
   1. With knowledge; in a knowing manner; intelligently;
      consciously; deliberately; as, he would not knowingly
      offend. --Strype.
      [1913 Webster]

   2. By experience. [Obs.] --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

knowingly
    adv 1: with full knowledge and deliberation; "he wittingly
           deleted the references" [syn: wittingly, knowingly]
           [ant: inadvertently, unknowingly, unwittingly]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "knowingly":
   advisedly, artfully, astutely, by design, cagily, calculatedly,
   cannily, circumspectly, cleverly, consciously, considerately,
   contemplatedly, cunningly, deliberately, designedly, discerningly,
   discreetly, eruditely, foxily, guilefully, in cold blood,
   insidiously, intelligently, intentionally, judiciously, learnedly,
   meditatedly, on purpose, on the sly, pointedly, premeditatedly,
   providently, prudently, purposefully, purposely, purposively,
   rationally, reasonably, sagaciously, sensibly, shiftily, shrewdly,
   slick, slyly, smartly, smoothly, studiously, subtilely, subtlely,
   thoughtfully, trickily, understandingly, voluntarily, warily,
   wilily, willfully, wisely, with forethought, with full intent,
   with intent, with malice aforethought, with purpose, wittingly



Bouvier's Law Dictionary, Revised 6th Ed (1856):

KNOWINGLY, pleadings. The word knowingly," or "well knowing," will supply
the place of a positive averment in an indictment or declaration, that the
defendant knew the facts subsequently stated; if notice or knowledge be
unnecessarily stated, the allegation may be rejected as surplusage. Vide
Com. Dig. Indictment, G 6; 2 Stra. 904; 2 East, 452; 1 Chit. Pl. *367; Vide
Scienter.