Translation guide
The English word "brain" can refer to the physical organ, intellectual capacity, or a smart person. This guide covers natural Japanese expressions for each meaning.
Referring to the physical brain inside the head.
The standard word for the brain as an organ. Used in medical, scientific, and everyday contexts.
The brain is protected by the skull.
脳の働きについて研究している。
I'm researching the functions of the brain.
Colloquial term for the brain, often used in casual conversation. Can sound slightly childish or informal.
頭をぶつけて脳みそが飛び出しそうだ。
I hit my head so hard my brains feel like they're going to pop out.
Referring to someone's intellectual capacity, often in phrases like "use your brain" or "he has a good brain."
Literally "head," but commonly used to mean intelligence or mental ability. Very natural in everyday speech.
彼は本当に頭がいい。
He's really smart. (lit. He has a good head.)
もっと頭を使いなさい。
Use your brain more.
Can also refer to intellectual capacity, but less common than 頭 in casual contexts. Often used in compounds or formal settings.
彼は明晰な脳の持ち主だ。
He has a clear/sharp brain.
Means "intelligence" or "intellectual faculty." More technical than 頭.
Referring to a person who is exceptionally smart, like "he's the brain of the team."
Means "brains" as in a smart person or the intellectual leader of a group. Often used in phrases like 頭脳集団 (think tank).
彼はチームの頭脳だ。
He's the brains of the team.
Refers to a person of exceptional intelligence or academic talent. Often used for students.
Means "genius." Stronger than 秀才, implying innate extraordinary intelligence.
Referring to animal brains eaten as food.
Used for animal brains in culinary contexts. Often specified with the animal name, e.g., 豚の脳 (pig's brain).
豚の脳を食べたことがありますか。
Have you ever eaten pig's brain?
Colloquial term also used for food, but can sound unappetizing or humorous.
English idioms like "rack one's brains" or "brainstorm" do not use 脳 directly. For "rack one's brains," use 頭を悩ませる (あたまをなやませる) or 知恵を絞る (ちえをしぼる). For "brainstorm," use ブレインストーミング or アイデアを出し合う (アイデアをだしあう).
When talking about intelligence or mental effort, 頭 (あたま) is more common and natural in everyday speech. 脳 (のう) is more anatomical or formal. Saying 頭がいい is the standard way to say "smart." 脳がいい is not idiomatic.
彼は脳に損傷を負った。
He suffered a brain injury.
彼女は素晴らしい頭脳の持ち主だ。
She has a brilliant brain.
頭を使え！
Use your brain!
I took a test to measure my IQ.
彼女は学校一の秀才だ。
She's the top brain in the school.
アインシュタインは天才だった。
Einstein was a genius.
魚の脳みそは小さいけど美味しい。
Fish brains are small but delicious.