I am not sure how many people actually know the real definition of 1st, 2nd, and 3rd world anymore. It is very possible many have never known.

When I question people who’ve use the term third world what they mean they most often respond indicating they do not know. They often explain means in developed or “behind the times”. This is not true.

In reality the terms First World, Second World, and Third World were originally used to divide the world's nations into three categories. The complete overthrow of the pre–World War II status quo left two superpowers (the United States and the Soviet Union) vying for ultimate global supremacy, a struggle known as the Cold War. They created two camps, known as blocs. These blocs formed the basis of the concepts of the First and Second Worlds. The Third World consisted of those countries that were not closely aligned with either bloc.
(From wiki)