Courage, spirit, or determination. She showed a lot of spunk by standing up to the bullies.
The biologist explained the role of spunk in reproduction.
(Austral., NZ, informal) A sexually attractive person. Everyone agreed the new teacher was an absolute spunk.
(Archaic) Tinder; touchwood, especially the dried, spongy matter of certain fungi used for kindling. The camper struck a spark and held it to the spunk to start the fire.