From The Collaborative International Dictionary of English v.0.48 [gcide]:
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.
[1913 Webster]
2. An inflammable temper; spirit; mettle; pluck; as, a man of
spunk. [Colloq.]
[1913 Webster]
A lawless and dangerous set, men of spunk, and
spirit, and power, both of mind and body. --Prof.
Wilson.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
spunk
n 1: material for starting a fire [syn: kindling, tinder,
touchwood, spunk, 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, spunk]