Translation guide
The English word 'intelligent' covers a range of meanings from raw intellectual ability to cleverness and good judgment. In Japanese, different words are used depending on whether you mean academic smartness, quick-wittedness, or wise decision-making.
Describing someone who is intellectually gifted, academically capable, or has a high IQ.
The most common and natural way to say someone is smart or intelligent. Used in everyday conversation.
He is really intelligent.
Often used for children or animals, implying cleverness and good sense. Can sound slightly cute or endearing.
That's an intelligent dog.
Means 'intellectual' and is often used to describe a person's appearance, interests, or atmosphere. More formal than 頭がいい.
She enjoys intellectual conversations.
A formal, literary word meaning wise and intelligent. Often used in writing or formal speeches.
He is a wise and intelligent leader.
Describing someone who thinks fast, is mentally agile, or comes up with clever solutions.
Literally 'head rotation is fast', this is the go-to phrase for quick-wittedness.
He's quick-witted, so he can answer any question immediately.
Means resourceful and quick-thinking, especially in handling situations. Slightly more formal.
Often used for children or pets, meaning clever and well-behaved. Can imply shrewdness in adults.
Describing decisions, actions, or people that demonstrate wisdom and sound judgment.
Describing intelligence in a particular area, often with a modifier.
The katakana word インテリジェント is used mainly in compound terms like インテリジェントビル (intelligent building) or in technical contexts. It is not used to describe people in natural Japanese.
He is intelligent. (unnatural)
頭がいい is the most general and neutral way to say someone is intelligent. 賢い often implies cleverness and good judgment, and is frequently used for children, animals, or in a slightly endearing way. For adults, 頭がいい is safer unless you want to emphasize wisdom or cuteness.
She's quick-witted, so she can handle troubles well.
What a clever child.