When you want to express a relaxed or calm feeling, you can use some of these synonyms for the word "chill." Instead of saying you feel chill, you can say you feel cool, collected, composed, or serene. If you want to say that something is easy-going, you can use mellow, laid-back, or casual. On the other hand, if you want to describe a cold environment, you can use frosty, icy, or brisk. If it's a creepy atmosphere that you want to convey, you can use eerie, spooky, or unsettling. In conclusion, there are many ways to express the concept of "chill" in your communication.