How to say "cool" in Chinese
酷！= "Cool!", transliteration from English
酷毙了！= "Cool to die for" (was a popular phrase in the 90s)
牛！ = literally means bull, but here means "genius"; used to describe people only



  他数学太牛了！He's so good at math!
  
  这个杂技演员太牛了！The acrobat is so talented!



太棒了！= literally "Too great!", or "Fantastic!"



  爸妈下周带我们去海边。Mom and Dad will take us to the beach next week.
  
  太棒了！Awesome!



帅！= "Handsome!" ("帅翻了" is also a popular phrase used among teenage girls. I don't know how much adults understand/like this usage.)
帅呆了！(was a popular phrase in the 90s)



  周杰伦已经过气了，现在最火的是许嵩。你看了她新出的MV了吗？Jay Chou is passé. Xu Song is what everybody's been talking about lately. Have you seen the music video he just posted?
  
  一个字，帅！(Literally:) I can only use one word to describe it - handsome!



爽！= what you say when you are feeling refreshed and comfortable (after having some ice-creams on a hot summer day, taking public revenge on your long-time enemy
爽死了！
真好！= "Really/truly good!"
真不错！= literally "really not bad"; "Really good!"
厉害！= used to express admiration of someone's skill (If you want to use it in a sentence, remember to say "他很厉害/他特别厉害/他超级厉害"; "他厉害" is incorrect.)