What is "feistier"

Usage examples of "feistier".

Now, I'm younger and feistier back then than I am now, and though it had started snowing before Halloween that year, now it was Thanksgiving and there was clean snow on the ground, fresh as anything, and I could see the buck's footprints.

He had mastered feistier beasts to the saddle, and he must-if he wished to Hold-prove equally capable at retraining.

He had mastered feistier beasts to the saddle, and he must—if he wished to Hold—prove equally capable at re training.