noun, noun or participle which takes 'suru'
Slangy, casual term for relaxing or hanging out in a low-key way. Often used as チルする or in compounds like チルい.
今日は家でチルしてる。
I'm just chilling at home today.
あのカフェ、すごくチルい
That café has a really chill vibe, doesn't it?