pugnacious

Learned borrowing from Latin pugnāci-, a stem of pugnax (“fond of fighting, aggressive, combative, pugnacious”) + English -ous (“suffix forming adjectives from nouns, denoting presence of qualities in any degree (typically an abundance)”). Pugnax is derived from pugnō (“to combat, fight; etc.”) + -āx (suffix forming adjectives denoting a tendency to do the actions of the verbs it is attached to); and pugnō from pugnus (“fist”) (ultimately from Proto-Indo-European *puǵnos, *puḱnos (from *pewǵ- (“to engage in a fistfight, punch; to poke, prick”)) + Latin -nus (suffix forming nouns)) + -ō (suffix forming regular first-conjugation verbs).