Source : Webster's Revised Unabridged Dictionary (1913)

Whence \Whence\, adv. [OE. whennes, whens (with adverbial s,
   properly a genitive ending; -- see {-wards}), also whenne,
   whanene, AS. hwanan, hwanon, hwonan, hwanone; akin to D.
   when. See {When}, and cf. {Hence}, {Thence}.]
   1. From what place; hence, from what or which source, origin,
      antecedent, premise, or the like; how; -- used
      interrogatively.

            Whence hath this man this wisdom?     --Matt. xiii.
                                                  54.

            Whence and what art thou?             --Milton.

   2. From what or which place, source, material, cause, etc.;
      the place, source, etc., from which; -- used relatively.

            Grateful to acknowledge whence his good Descends.
                                                  --Milton.

   Note: All the words of this class, whence, where, whither,
         whereabouts, etc., are occasionally used as pronouns by
         a harsh construction.

               O, how unlike the place from whence they fell?
                                                  --Milton.

   Note: From whence, though a pleonasm, is fully authorized by
         the use of good writers.

               From whence come wars and fightings among you?
                                                  --James iv. 1.
         Of whence, also a pleonasm, has become obsolete.

Source : WordNet®

whence
     adv : from what place or origin or source; "whence did he come?";
           "whence comes this splendid feast?"; "sketches the
           lawless society whence the ballads sprang"-DeLancey
           Ferguson [syn: {wherefrom}]