noun, noun which may take the genitive case particle 'no'
depending on one's mood; as one feels like
Used when a decision or action is based on how one feels at the moment, often implying a lack of fixed plan or principle.
Let's decide today's plans depending on how we feel.
His motivation depends on his mood.
気分 means 'mood' or 'feeling'; 気分次第 adds the sense of 'depending on' that mood.
次第 is a suffix meaning 'depending on'; 気分次第 is a common compound using it.
Compound of 気分 (mood, feeling) and 次第 (depending on).