chill out verb2 •(slang) To relax or take time out; to calm down; reduce or go easy on something.Since I'm between projects, I think I'll just chill out.I wish I could chill out about the neighbor's barking dog, but it wakes me up every night. •(slang, old-fashioned) To hang out; spend time together with another person or group.Hey, we should chill out together this weekend. formschilled out · chilling out · chills out