If someone is pugnacious, they are very ready to argue or to fight. They do not wait to be pushed; they go looking for a clash. It can be physical — a pugnacious little dog that barks at every passer-by — but more often now it is about words: a pugnacious politician, a pugnacious essay. It is a fairly formal adjective, a little bookish. Stronger than argumentative, more personal than aggressive: the old picture is of someone with their fists up. Though actually, you can be pugnacious without throwing a punch; the fight can be all talk. It comes from Latin for fighting with the fist, so it shares a deep root with pugilist, but it is not a boxing word in modern English. Calling someone pugnacious is rarely a simple compliment. It can mean they have fight in them, or that they tire everyone out.