But the next generation didn't want to be like their parents, so they developed the opposite term, "cool," to be used with the same meaning.
Over the years both terms have become accepted parts of the English language and are both still currently used, with slight changes in meaning. "Hot" is now used mostly with regard to physical attractiveness or things that are extreme. "Cool" is so common that the meaning has become mild and it's often a synonym for "okay."
I wonder if a different word regarding temperature will someday become the new slang for things that were once called hot or cool. "Cold" already has a different connotation so that probably won't do.
Maybe the new term will be "luke."