The Collaborative International Dictionary of English v.0.48:

Prudent \Pru"dent\, a. [L. prudens, -entis, contr. from
   providens: cf. F. prudent. See Provident.]
   1. Sagacious in adapting means to ends; circumspect in
      action, or in determining any line of conduct; practically
      wise; judicious; careful; discreet; sensible; -- opposed
      to rash; as, a prudent man; dictated or directed by
      prudence or wise forethought; evincing prudence; as,
      prudent behavior.
      [1913 Webster]

            Moses established a grave and prudent law. --Milton.
      [1913 Webster]

   2. Frugal; economical; not extravagant; as, a prudent woman;
      prudent expenditure of money.
      [1913 Webster]

   Syn: Cautious; wary; circumspect; considerate; discreet;
        judicious; provident; economical; frugal.
        [1913 Webster]

WordNet (r) 3.0 (2006):

prudent
    adj 1: careful and sensible; marked by sound judgment; "a
           prudent manager"; "prudent rulers"; "prudent hesitation";
           "more prudent to hide than to fight" [ant: imprudent]

Moby Thesaurus II by Grady Ward, 1.0:

126 Moby Thesaurus words for "prudent":
   Argus-eyed, Scotch, advisable, alert, all ears, all eyes,
   anticipant, anticipatory, attentive, aux aguets, bland, canny,
   careful, cautious, chary, cheeseparing, circumspect, clairvoyant,
   conserving, considerate, custodial, deliberate, discerning,
   discreet, discriminating, discriminative, divinatory, eagle-eyed,
   economic, economical, economizing, enlightened, farseeing,
   farsighted, forehanded, foreknowing, foreseeing, foresighted,
   forethoughted, forethoughtful, frugal, gentle, gingerly, guarded,
   hawk-eyed, heedful, hesitant, intuitive, judgmatic, judicial,
   judicious, keen-eyed, labor-saving, leaving out nothing, lidless,
   longsighted, mild, mild as milk, mindful, moderate, money-saving,
   noncommittal, nonviolent, observant, on guard, on the lookout,
   on the watch, open-eyed, overlooking no possibility, pacifistic,
   parsimonious, pawky, peaceable, peaceful, penny-wise, politic,
   precognitive, precognizant, prepared, prescient, provident,
   providential, prudential, ready, reasonable, reflecting,
   reflective, regardful, safe, sagacious, sage, sane, sapient,
   saving, scrimping, sensible, sharp-eyed, shrewd, skimping,
   sleepless, slow to act, sober, soft, spare, sparing, tactical,
   tame, temperate, tentative, thorough, thoughtful, thrifty,
   time-saving, unadventurous, uncommunicative, undaring,
   unenterprising, unprecipitate, unwasteful, vigilant, wary,
   watchful, well-advised, well-judged, wise, with open eyes