The Collaborative International Dictionary of English v.0.48:

Virtuous \Vir"tu*ous\ (?; 135), a. [OE. vertuous, OF. vertuos,
   vertuous, F. vertueux, fr. L. Virtuous. See Virtue, and cf.
   Virtuoso.]
   1. Possessing or exhibiting virtue. Specifically:
      [1913 Webster]
      (a) Exhibiting manly courage and strength; valorous;
          valiant; brave. [Obs.]
          [1913 Webster]

                Old Priam's son, amongst them all, was chiefly
                virtuous.                         --Chapman.
          [1913 Webster]
      (b) Having power or efficacy; powerfully operative;
          efficacious; potent. [Obs.] --Chaucer.
          [1913 Webster]

                Lifting up his virtuous staff on high,
                He smote the sea, which calm['e]d was with
                speed.                            --Spenser.
          [1913 Webster]

                Every virtuous plant and healing herb. --Milton.
          [1913 Webster]
      (c) Having moral excellence; characterized by morality;
          upright; righteous; pure; as, a virtuous action.
          [1913 Webster]

                The virtuous mind that ever walks attended
                By a strong siding champion, conscience.
                                                  --Milton.
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   2. Chaste; pure; -- applied especially to women.
      [1913 Webster]

            Mistress Ford . . . the virtuous creature, that hath
            the jealous fool to her husband.      --Shak.
      [1913 Webster] -- Vir"tu*ous*ly, adv. --
      Vir"tu*ous*ness, n.
      [1913 Webster] Virulence

WordNet (r) 3.0 (2006):

virtuous
    adj 1: morally excellent [ant: wicked]
    2: in a state of sexual virginity; "pure and vestal modesty"; "a
       spinster or virgin lady"; "men have decreed that their women
       must be pure and virginal" [syn: pure, vestal, virgin,
       virginal, virtuous]

Moby Thesaurus II by Grady Ward, 1.0:

130 Moby Thesaurus words for "virtuous":
   Christian, advantageous, angelic, auspicious, beneficial,
   benevolent, blameless, blotless, bon, bonny, braw, bueno, capital,
   chaste, clean, cleanly, cogent, commendable, creditable, decent,
   effectual, efficacious, efficient, elegant, erect, estimable,
   ethical, excellent, exemplary, expedient, fair, fair-minded,
   faithful, famous, faultless, favorable, fine, full of integrity,
   godly, good, goodly, grand, guiltless, healthy, helpful,
   high-minded, high-principled, highly respectable, honest,
   honorable, immaculate, in the clear, incorruptible, inculpable,
   innocent, inviolate, irreproachable, just, kind, laudable,
   law-abiding, law-loving, law-revering, manly, moral, moralistic,
   nice, noble, pleasant, principled, profitable, proper, pure,
   pure in heart, purehearted, regal, reputable, respectable, right,
   right-minded, righteous, royal, saintlike, saintly, scrupulous,
   seraphic, sexually innocent, sinless, skillful, snowy, sound,
   splendid, spotless, stainless, sterling, straight, taintless, true,
   true-dealing, true-devoted, true-disposing, true-souled,
   true-spirited, truehearted, trustworthy, unblamable, unblemished,
   unblotted, uncorrupt, uncorrupted, undefiled, unimpeachable,
   unsoiled, unspotted, unstained, unsullied, untainted, untarnished,
   upright, uprighteous, upstanding, useful, valid, very good, virgin,
   virginal, white, without reproach, worthy, yeomanly