気分
きぶん · kibun · JLPT N4 · noun
feeling
気分 = 気 spirit/energy + 分 portion: your share of spirit right now
気 (ki) is the same spirit/energy found in 元気 and 天気; 分 (bun) means a part or portion. Your mood is the portion of ki you have at the moment. Common in 気分がいい (feel good) and 気分が悪い (feel unwell).
分 — knife 刀 + eight 八 (split apart)
分 originally depicted a knife (刀) cutting something into two parts, shown by 八 above (which itself meant 'divide'). The core sense is 'to divide' or 'split', from which extended meanings like 'portion', 'minute', and 'part' developed. Pronounced fèn, it carries the sense of an allotted share.