1) (noun) A person who goes on and on with little regard to how interesting they really are.
2) (noun) A lengthy conversation that is ultimately of little import.
1) “I got cornered by a real yaccarino at the party. It was so bad I considered chewing my arm off to escape.”
2) “You didn’t miss much: we opened a couple of bottles of white and had ourselves a real yaccarino.”
Someone paid to make reassuring noises in order to distract from the malice or incompetence of the ruling class.
The Better Angels of Our Nature, by Steven Pinker, was a genre defining piece of Yaccarino lit, fervently arguing that everything is getting better and better despite overwhelming evidence that Pinker's wealthy friends were making the world much, much worse.