Translation guide
Describes behavior, attitudes, or qualities that are childish in an immature or negative way. Focuses on how to express immaturity, pettiness, or lack of emotional development in Japanese.
To describe someone or something as acting in a way that is immature, petty, or lacking adult emotional control, similar to a child.
The most direct and common translation for 'infantile' when describing immature behavior or thinking. Often used critically.
To refer to something related to infancy or early childhood, often in medical or psychological contexts.
While 幼児 means 'infant' or 'toddler', using 幼児の to describe behavior sounds unnatural. Use 幼稚 or 子供っぽい for immaturity.
彼の考え方は幼稚だ。
His way of thinking is infantile.
Stop making such infantile excuses.
Means 'childish' or 'childlike', but often carries a negative nuance of immaturity when used for adults. Slightly less formal than 幼稚.
His behavior is infantile.
Literally 'not adult-like'. Used to criticize someone for lacking maturity or dignity expected of an adult. Very common in spoken Japanese.
It's infantile to get angry over something like that.
Means 'immature' or 'unripe'. Can refer to skills, personality, or emotional development. More formal and often used in written contexts.
His emotional immaturity is the problem.
I have almost no infantile memories.
Medical term for 'child' or 'infantile', used in compound words like 小児科 (pediatrics). Can appear in terms like 'infantile paralysis'.
Infantile paralysis is polio.