Ways to say it
| Japanese | Romanization (Wiktionary) | IPA |
|---|---|---|
| リアクション | riakushon | [ɾʲia̠kɯ̟̊ɕõ̞ɴ] (narrow) |
| 反応 | hannō | [hã̠nːo̞ː] (narrow) |
| 反動 | handō | [hã̠ndo̞ː] (narrow) |
Japanese uses different words for reaction depending on whether you are describing a physical process, a social behavior or a physical recoil. 反応 is the most common and neutral term, specifically used for scientific, biological or physical reactions. In a social or entertainment context, リアクション refers to a person's outward behavioral response. For a physical recoil or a social/political backlash, use 反動.
Which one should you use?
反応 is used for scientific, biological or physical reactions, such as a chemical or an allergic reaction. リアクション describes a person's outward behavioral reaction or response, often in a social or entertainment context. 反動 refers to a physical recoil or a social and political backlash or counteraction.
How does it change in a sentence?
The term 反応力 specifically focuses on a person's ability to react quickly. To describe someone who is expressive or reacts enthusiastically, you can use the phrase リアクションがいい, meaning 'to have a good reaction'.
How do you pronounce it?
riakushon
Did you know?
- The word 反応 was actually invented by a biologist named Iwakawa Tomotarō in 1884 to translate the scientific concept of 'reaction' from English.
- While リアクション means 'reaction', it is often used in Japan to describe 'over-reacting' or performing exaggerated gestures for the sake of a camera or an audience.
- The term 反動 is used for both the physical recoil of a gun and the societal backlash of a political movement, linking physical physics to social behavior.
Examples in context
- 酸は金属に触れると化学反応を起こす。When acid comes in contact with metal, it causes a chemical reaction.The first sentence shows how to use 反応 regarding a chemical reaction.Tatoeba #4919673 by huizi99, translation #4923505 by gustonrankin
- 酸が金属に触れると化学反応が起こる。When acid touches metal, a chemical reaction happens.The second sentence demonstrates the use of 反応 in a sentence about a chemical reaction happening.Tatoeba #4919674 by huizi99, translation #4922024 by gustonrankin
- アレルギー反応が起きると、どうなりますか？What happens when you have an allergic reaction?The third sentence uses 反応 to discuss an allergic reaction.Tatoeba #9870213 by bunbuku, translation #9849604 by NurseMeeks
- 彼の反応は冷静でしたHis reaction was calm
- 彼女の面白いリアクションを見たI saw her funny reaction
- 彼は反応力が抜群だHe has excellent reaction skills
- 彼はドヤ顔で勝利を宣言したHe declared victory with a triumphant expression
- 7 more sentences on Tatoeba
Example conversation
Talking about a funny video they both watched.
- 大翔 Hirotoこの動画、リアクションが面白すぎるね。Kono dōga, riakushon ga omoshirosugiru ne.The reactions in this video are way too funny.
- 陽葵 Himari本当だね。びっくりしすぎだよ。Hontō da ne. Bikkuri shisugi dayo.You're right. They're way too surprised.
- 大翔 Hiroto陽葵はどんなリアクションをする？Himari wa donna riakushon o suru?What kind of reaction would you have, Himari?
- 陽葵 Himari私はたぶん、笑っちゃうと思うな。Watashi wa tabun, warachau to omou na.I think I would probably just laugh.
Sources
- Wiktionary, “reaction” translations and entries リアクション, 反応, 反動, CC BY-SA 4.0, dump of 2026-09-26.
- Word origins: Wiktionary entries リアクション, 反応, CC BY-SA 4.0.
- Example sentences: Tatoeba CC BY 2.0 FR.
