expression, noun
good feeling; pleasant sensation
Refers to a comfortable, pleasant physical or emotional state. Often used in set phrases like いい気持ちになる or いい気持ちだ.
温泉に入って、いい気持ちになった。
I felt really good after getting into the hot spring.
風が気持ちよくて、本当にいい気持ちだ。
The breeze feels nice; it's such a pleasant feeling.
気持ちいい is an i-adjective meaning 'feels good', while いい気持ち is a noun phrase meaning 'a good feeling'.
Phrase composed of いい (good) and 気持ち (feeling).