noun
Refers to the philosophical concept of egoism or the general attitude of prioritizing oneself. Often used in discussions of ethics or personality.
彼の行動はエゴイズムに基づいている。
His actions are based on egoism.
利己主義 is a more formal, Sino-Japanese term for egoism or selfishness, often used in philosophical or ethical contexts. エゴイズム is a common loanword with a slightly broader, everyday usage.
エゴイスト refers to an egoist (a person), while エゴイズム refers to the concept or attitude of egoism.
Borrowed from English 'egoism', ultimately from Latin 'ego' (I).