“Cool” is a “new-generation” word used to describe something or anything that a person likes or finds original, fancy, surprising, trendy, or fun. It is used to describe something that appeals to the person: a thing, an idea, another person… “Cool” depends on a person’s tastes, so every person has a different set of “cool things”.
I first heard the word “cool” from my cousin way back when we were kids. Back then, we would have probably said: “Look at that cool robot” or “I like that movie, it’s cool!”. Kids mostly use “cool” to describe toys, games, movies, or people that they like. Teens however, have different visions.
For most superficial teens, “cool” is about appearance and trend. Many teens try to be “cool” by dressing in a certain way and doing certain actions, thinking that it will make them popular. So a stereotypical “cool guy” these days is one that’s “wearin” some baggy jeans (that are barely hanging on) and some kind of ridiculous top. He’d probably have a couple of tattoos and piercings, and would be saying things like: “Yo!” or “Whassup man?” or “Chill out dude!”. It would also help to smoke, drink, or drive a convertible car without a license. For these people, it would also help to use special colors or specific brands of items, (like Oakley’s for sunglasses, Eastpak for bags, or always wearing black…). They think “cool” is “perfect”.
Classical people (the old generation, or people who take life too seriously) also have a different vision of “cool”. If these people use that word at all, they use its literal meaning, or use it to describe a calm, quiet person.
I, on the other hand, am not a very classical person, so I also have a different vision. To me, a person is “cool” if he/she is original, stylish, classy, and nice. I also refer to the music I listen to as “cool”, and probably everything else that I might like or find interesting. So to me, things like rock and techno music, a new fancy sports car, meeting a celebrity, or getting an A on an exam or assignment… are cool! And things like pollution, war, crowds, hypocrites, and boring books are not cool.
Because “cool” depends on tastes and likes, it has no one definition. But it is useful because it expresses one’s ideas and tells about a person’s tastes, so it’s… cool! And because it’s harmless, it is not wrong to try to be “cool”, but let’s try not to over-do it.
Here’s a link to the word’s Urban Dictionary definition:
http://www.urbandictionary.com/define.php?term=cool