Etymology of Punk and Spunk

The term "spunk" originated in the early 1600's in the British Isles meaning "a spark," having been adopted from the Gaelic spong for "tinder," which in turn comes from the Latin spongia. The Latin appears to be derived from how closely the popular kindling touchwood resembles natural sponges. "Spunk" became a colloquial term for courage and pluck in the late 18th century, assumably with the sense that the person showed some spark of life. The vulgar use of the term appeared about a century ago and is rarely used in this sense outside of the United Kingdom.

As it turns out, it appears likely that "spunk" shares a similar etymology with "punk," although the former had a decidedly less positive sense until recently. The term "punk" fist appears in the United States just before the turn of the 19th century to mean "inferior, bad or worthless," having been used formerly to denote low quality wood that was not good for anything other than kindling. Shortly into the 20th century, young adults and children were described as "punk kids" who became hoodlums and were of essentially worthless in the eyes of productive society.

It's also interesting to note that both the terms "punk" and "fagot" were originally used to describe low quality would meant for kindling...

Notes: There's actually a couple other etymologies out there for "punk" out there, but this is the only one I could find shows a clear evolution of the terms over recent history. Also, I seem to recall that they used to pack fireworks with a slow burning stick called a "punk" that was used to light fuses, but I haven't taken the time to double check on that one.