Source : Webster's Revised Unabridged Dictionary (1913)

Ingenuous \In*gen"u*ous\, a. [L. ingenuus inborn, innate,
   freeborn, noble, frank; pref. in- in + the root of gignere to
   beget. See {Genius}, and cf. {Ingenious}.]
   1. Of honorable extraction; freeborn; noble; as, ingenuous
      blood of birth.

   2. Noble; generous; magnanimous; honorable; upright;
      high-minded; as, an ingenuous ardor or zeal.

            If an ingenuous detestation of falsehood be but
            carefully and early instilled, that is the true and
            genuine method to obviate dishonesty. --Locke.

   3. Free from reserve, disguise, equivocation, or
      dissimulation; open; frank; as, an ingenuous man; an
      ingenuous declaration, confession, etc.

            Sensible in myself . . . what a burden it is for me,
            who would be ingenuous, to be loaded with courtesies
            which he hath not the least hope to requite or
            deserve.                              --Fuller.

   4. Ingenious. [Obs.] --Shak.

   Note: (Formerly) printers did not discriminate between . . .
         ingenuous and ingenious, and these words were used or
         rather printed interchangeably almost to the beginning
         of the eighteenth century. --G. P. Marsh.

   Syn: Open; frank; unreserved; artless; plain; sincere;
        candid; fair; noble; generous.

   Usage: {Ingenuous}, {Open}, {Frank}. One who is open speaks
          out at once what is uppermost in his mind; one who is
          frank does it from a natural boldness, or dislike of
          self-restraint; one who is ingenuous is actuated by a
          native simplicity and artlessness, which make him
          willing to confess faults, and make known his
          sentiments without reserve. See {Candid}.

Source : WordNet®

ingenuous
     adj 1: characterized by an inability to mask your feelings; not
            devious; "an ingenuous admission of responsibility"
            [syn: {artless}] [ant: {disingenuous}]
     2: lacking in sophistication or worldliness; "a child's
        innocent stare"; "his ingenuous explanation that he would
        not have burned the church if he had not thought the
        bishop was in it" [syn: {innocent}]