Translation guide
How to express 'become erect' in Japanese, from clinical terms to slang, with notes on usage and context.
The penis becomes erect due to sexual arousal.
Casual, colloquial verb meaning 'to stand up', commonly used for erections in informal speech.
あの子を見ると、すぐ立っちゃう。
When I see that girl, I get hard right away.
Literally 'to become hard', a common euphemistic way to say 'become erect'.
ちょっと触っただけで硬くなった。
It got hard just from a little touch.
Slang variant of 勃起する, used in very casual or vulgar contexts. Often seen in manga or adult content.
エロ本見て勃った。
I got a boner looking at a porn mag.
To describe a clitoris becoming erect, typically in medical or educational contexts.
Same verb as for penile erection; used in medical or anatomical descriptions.
性的興奮によりクリトリスが勃起する。
The clitoris becomes erect due to sexual arousal.
To describe hair standing on end, as in goosebumps or animal fur bristling.
Means 'to stand on end' or 'bristle', used for hair or fur due to cold, fear, or anger.
寒さで鳥肌が立って、毛が逆立った。
I got goosebumps from the cold and my hairs stood on end.
猫が怒って毛を逆立てた。
The cat bristled its fur in anger.
Simple phrase meaning 'hair stands up', often used for goosebumps or fear.
怖くて全身の毛が立った。
I was so scared the hair all over my body stood up.
To describe something non-living rising or standing upright, like a plant or structure.
Means 'to stand upright' or 'to rise vertically', used for objects, plants, or posture.
その塔は地面から直立している。
The tower stands erect from the ground.
Dramatic verb meaning 'to rise toweringly' or 'to stand erect', often for mountains or tall structures.
岩山がそそり立っている。
The rocky mountain stands erect.
When describing objects or plants standing upright, do not use 勃起する, as it strongly implies sexual erection. Use 直立する or そそり立つ instead.
その花はまっすぐ直立している。
The flower stands erect.
In everyday conversation, 立つ or 硬くなる are more natural than 勃起する, which sounds clinical. Use 勃起する in medical contexts or when speaking formally.