feistiest

/F AY1 S T IY0 AH0 S T/
adjective
  1. 1

    Tenacious, energetic, spunky.

  2. 2

    Belligerent; prepared to stand and fight, especially in spite of relatively small stature or some other disadvantage.

  3. 3

    Easily offended and ready to bicker.

Source: https://en.wiktionary.org/wiki/feistiest, https://en.wiktionary.org/wiki/feisty