Spunk?

I never realized that people still used the word spunk. I made some of my friends fill out fun surveys because about every six months I like to know what my friends think of me. A bunch have to do with personality and a bunch of friends filled in that I had "spunk." What is this spunk they speak of? Sort of makes me feel like I'm jumpy. A.D.D., too much energy sort of. It also envoked thoughts of the eighties, like Punky Brewster would have had spunk. I just htought it was interesting that they thought I had spunk. I'm going to start using that word more often.