Translation guide
How to express 'become erect' in Japanese, from clinical terms to slang, with notes on usage and context.
To describe a penis becoming erect, in medical, neutral, or casual contexts.
Standard verb for 'to become erect'. Used in medical, formal, and neutral contexts. Can be used for both humans and animals.
I often get an erection in the morning.
The penis becomes erect due to sexual arousal.
Casual, colloquial verb meaning 'to stand up', commonly used for erections in informal speech.
When I see that girl, I get hard right away.
Literally 'to become hard', a common euphemistic way to say 'become erect'.
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.
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.
The clitoris becomes erect due to sexual arousal.
To describe hair standing on end, as in goosebumps or animal fur bristling.
To describe something non-living rising or standing upright, like a plant or structure.
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.
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.
猫が怒って毛を逆立てた。
The cat bristled its fur in anger.
I was so scared the hair all over my body stood up.
The rocky mountain stands erect.