Source : Webster's Revised Unabridged Dictionary (1913)

Spunk \Spunk\ (sp[u^][ng]k), n. [Gael. spong, or Ir. sponc,
   tinder, sponge; cf. AS. sponge a sponge (L. spongia), sp[=o]n
   a chip. Cf. {Sponge}, {Punk}.] [Written also {sponk}.]
   1. Wood that readily takes fire; touchwood; also, a kind of
      tinder made from a species of fungus; punk; amadou. --Sir
      T. Browne.

   2. An inflammable temper; spirit; mettle; pluck; as, a man of
      spunk. [Colloq.]

            A lawless and dangerous set, men of spunk, and
            spirit, and power, both of mind and body. --Prof.
                                                  Wilson.

Source : WordNet®

spunk
     n 1: material for starting a fire [syn: {kindling}, {tinder}, {touchwood},
           {punk}]
     2: the courage to carry on; "he kept fighting on pure spunk";
        "you haven't got the heart for baseball" [syn: {heart}, {mettle},
         {nerve}]