[Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/dictionaries/school/w/reaction.html) [home](https://md.mova.elamur.ai/free/en/) / [dictionaries](https://md.mova.elamur.ai/free/en/dictionaries/) / [The school dictionary](https://md.mova.elamur.ai/free/en/dictionaries/school/) / reaction [← R](https://md.mova.elamur.ai/free/en/dictionaries/school/R/) # reaction «reaction» in Mova's school dictionary: **What someone says, does or feels because of something…** — its meaning for a pupil, its sense in the lessons and examples, with 5 sentences of Mova's corpora that use it. ### part of speech noun (a reaction, reactions) ### meaning for a pupil 1) What someone says, does or feels because of something that has happened: her reaction to the news was a big smile. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#m1) 2) In science, a chemical reaction is when substances change into new substances, like vinegar and bicarbonate of soda fizzing. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#m2) 3) An allergic reaction is when the body responds badly to something, such as nuts or a bee sting. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#m3) 4) How quickly you respond: fast reactions. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#m4) 5) In forces, a reaction is the push back in the opposite direction. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#m5) 6) A reaction can also be a movement that turns back against a change or an earlier way of doing things. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#m6) ### sense in the lessons In science, signs of a chemical reaction include fizzing (a gas), a colour change, heat or light, or a new solid forming; burning and rusting are reactions that cannot be undone. In health, an allergic reaction can cause a rash, swelling or trouble breathing; a severe one (anaphylaxis) is an emergency — call for help and an adult may use an adrenaline pen. In sport and games, quick reactions help you catch a ball. In stories, a character's reaction shows how they feel. Phrases: "chemical reaction", "allergic reaction", "a quick reaction", "reaction time", "chain reaction". ### examples - What was your reaction when you saw the surprise? [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x1) - Mixing vinegar and baking soda causes a fizzy reaction. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x2) - She had an allergic reaction to the peanuts. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x3) - Rusting is a slow chemical reaction. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x4) - Goalkeepers need fast reactions. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x5) - His reaction was to burst out laughing. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x6) - We measured our reaction times with a falling ruler. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x7) - The fizzing told us a reaction was happening. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x8) - When the Hindu reaction against Buddhism came, the Brahmins adapted these, with the omission of Buddha as the central figure. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/#x9) ### note Countable: a reaction, reactions. Verb: react; adjective: reactive. Melting and dissolving are usually changes, not chemical reactions, because no new substance is made. Any sign of a bad allergic reaction (swelling of lips or tongue, wheezing) needs an adult and emergency help at once. ### In the corpora - [A firework is a very fast chemical reaction that makes hot gases, light, heat, noise and smoke.](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/9-changes-you-can-and-cannot-undo/13/) - [Breathing and burning are the same kind of reaction: food or fuel joins with oxygen, giving energy, carbon dioxide and water.](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/11-the-candle-and-burning/12/) - [An allergic reaction to a sting needs a doctor straight away.](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/16-alkalis-and-soda/14/) - [Carbon dioxide is heavier than air, so a balloon filled with it from the reaction does not float.](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/18-the-fizz-vinegar-lemon-and-soda/13/) - [Cold slows down bacteria, mould and chemical reactions, so food lasts longer in the fridge.](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/23-browning-apples-rotting-and-mould/13/) ### Trees and pragmatics [Every meaning and example of «reaction» parsed by Mova](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/reaction/), each sentence with its dependency tree and frames.