feisty

Concise Oxford English Dictionary © 2008 Oxford University Press:
feisty /ˈfʌɪsti/

▶adjective (feistier, feistiest) spirited and exuberant.

– derivatives
feistily adverb,
feistiness noun.

– origin C19: from earlier feist, fist ‘small dog’, from fisting cur or hound, a derogatory term for a lapdog, from ME fist ‘break wind’; cf. fizzle.