individualism
A social or philosophical stance that values individual rights, freedom, and self-reliance over collective control. Often contrasted with 集団主義 (collectivism).
America is said to be a country with strong individualism.
A balance between individualism and collectivism is important.
A less common, often negative usage where 個人主義 is used loosely to mean selfishness or putting one's own interests first. More precise terms are 利己主義 or 自己中心. Cross-referenced with 利己主義.
See also: 利己主義
His behavior is more like egoism than individualism.
利己主義 explicitly means egoism or selfishness, while 個人主義 primarily means individualism as a social philosophy. Using 個人主義 for selfishness is a loose, often negative usage.
集団主義 is collectivism, the opposite of 個人主義 in social philosophy.
methodological individualism
Compound of 個人 (individual) + 主義 (principle, -ism). A Meiji-era calque from Western political philosophy.