Sentence:  “I reckon I′m as good as a mule,” he declared. “Maria knows what that desert is as well as we do, but she′s got more <WSD>spunk</WSD> than either of us. I'm not going to let any mule show more <WSD>spunk</WSD> than me.” 
Meaning of the word marked with <WSD> tags:  Courage; spirit; mettle; determination.