The culture of first world nations however, is completely fubar, has been since before all of us were born, and will probably continue to be long after we're all dead. (second and third world nations are also completely broken, but we expect that.)
It's the same kind of nonsense when people say "We've destroyed the planet!" No we haven't, we destroyed our own survivability in our own habitat, but the planet _is fine_, and will shake us all off some day without so much as a thought about it. The internet is equally indifferent and unaffected by our stupid capitalism problems.
So "second world" countries are those which are not quite stone-age savage, but are still noticably behind.
So an example of a "Second world" nation would be the United Kingdom, which enjoys many of the modern luxuries of the first world, and much of the social freedoms and progress, and yet still suffers under a completely irrational monarchy and lacks essential freedoms such as the right to self defense. As citizens of the United Kingdom are completely forbidden from keeping arms for the sole purpose of defense of self, family, and property, they are essentially servants of the state. Such a nation cannot then be justly described as "first world", as real first world nations such as the United States have enjoyed these additional freedoms for many generations now.
If my definition is not "official" then I apologize, nobody ever really explained the meaning of the phrases to me and my understanding is simply based on 3 decades of contextual usage. The implication is that there is a single path of progress which all nations are basically following. The first world is setting the example, and the rest are following our lead.
('that we still have such a long way to go is one of the reasons it's so amazing we haven't nuked ourselves to extinction yet :)')