pugnacious -- Hayden

pug·na·cious  (pg-nshs) adj. Combative in nature; belligerent. See Synonyms at belligerent. [From Latin pugnx, pugnc-, from pugnre, to fight, from pugnus, fist; see peuk- in Indo-European roots.] pug·nacious·ly adv. pug·nacious·ness, pug·naci·ty (-ns-t) n.

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Though not generally pugnacious, Hayden once punched an older boy on the school bus who was harassing him.