Translation guide
In Japanese, expressing 'selfishness' depends on whether you are describing someone's personality, a specific selfish action, or a child's behavior. The most common word is わがまま, which can be used for both adults and children. Other words like 自分勝手 and 利己的 carry stronger negative connotations or are more formal.
He is selfish.
Don't be selfish.
Describing someone who does what they want without considering others, or a specific selfish act.
The most common and versatile word for selfishness. Can describe a person's character or a specific selfish demand/action. Often used for children, but also for adults.
He is selfish.
Don't be selfish. / Don't make selfish demands.
Emphasizes acting only for one's own convenience, without regard for others. Stronger negative nuance than わがまま.
Please stop your selfish behavior.
Formal, often used in written or academic contexts. Means 'egoistic' or 'self-interested'.
selfish motives
Describing a person who is fundamentally self-centered or egotistical.
Describing a child's selfish behavior, often implying they are spoiled.
Referring to a specific instance of selfishness, like a request or action.
To say something selfish, to make a selfish demand.
Even if you say such selfish things, I don't know what to do.
To do something selfish, to act selfishly.
He only does selfish things.
わがまま is often used for personal desires and can be somewhat childish or emotional. 自分勝手 emphasizes acting without considering others' convenience, and is more strongly negative. 自分勝手 is rarely used for children.
The English noun 'selfishness' is often best translated as an adjective (わがままな) or verb phrase (わがままを言う) in Japanese. Using the noun form わがまま is also common, but other abstract nouns like 利己主義 (egoism) are more formal and less conversational.