Reaction may refer to a process or to a response to an action, event, or exposure:

Physics and chemistry

Chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

Nuclear reaction In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformatio ...

Reaction (physics) As described by the third of Newton's laws of motion of classical mechanics, all forces occur in pairs such that if one object exerts a force on another object, then the second object exerts an equal and opposite reaction force on the first. The th ...

, as defined by Newton's third law * Chain reaction (disambiguation).

Biology and medicine

Adverse drug reaction An adverse drug reaction (ADR) is a harmful, unintended result caused by taking medication. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs. The meaning of this term ...

Allergic reaction Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...

* Reflex, neural reaction *

Hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over-reaction of the immune ...

, immune reaction * Intolerance (disambiguation) * Light reaction (disambiguation).

Psychology

Emotion Emotions are mental states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or suffering, displeasure. There is currently no scientific ...

al, reaction *

Reactivity (behaviour) Proactivity or proactive behavior refers to self-initiated behavior that endeavours to solve a problem before it has occurred. Proactive behavior involves acting in advance of a future situation, rather than reacting. It refers to taking control o ...

* Proactivity, opposite of reactive behaviour *

Reactive attachment disorder Reactive attachment disorder (RAD) is described in clinical literature as a severe and relatively uncommon disorder that can affect children, although these issues do occasionally persist into adulthood.DSM-IV-TR (2000) American Psychiatric Ass ...

Politics and culture

* Reactionary, a political tendency * Reaction video * Commentary (disambiguation).

Proper names and titles

* ''Reaction'' (album), a 1986 album by American R&B singer Rebbie Jackson ** "Reaction" (song), the title song from the Rebbie Jackson album *"Reaction", a single by

Dead Letter Circus Dead Letter Circus are an Australian alternative rock band from Brisbane, Queensland. Their 2010 debut album ''This Is the Warning'' debuted at No. 2 on the Australian album charts and spawned a number of singles that were played heavily o ...

ReAction GUI ReAction GUI is the widget toolkit engine that is used in AmigaOS 3.2-4.1. It is an evolution of ClassAct, which is an object-oriented system of classes that enhanced the aspect of the Workbench 2.0 GUI of AmigaOS. History The native Amiga win ...

, a GUI toolkit used on AmigaOS * Reaction.life, a political news and commentary website edited by Iain Martin * Reaction Records, a record label *''

TNA Reaction ''TNA Reaction'' is an American professional wrestling-focused documentary-style television program by Total Nonstop Action Wrestling (TNA) that aired in the United States and Canada on Spike. The show aired two pilot episodes and a twenty-episo ...

'', a former documentary show of TNA Wrestling (now known as Impact Wrestling) behind the scenes * Reaction (''The Spectacular Spider-Man''), an episode of the American animated television series ''The Spectacular Spider-Man'' *''

The Reaction ''The Reaction'' is the 12th book in the ''Animorphs'' series, written by K.A. Applegate. It is narrated by Rachel. Plot summary At the zoo, Rachel and Cassie witness a boy fall into the crocodile pit. Rachel jumps into the pit to rescue hi ...

'', a novel in the ''Animorphs'' series *'' ''Reactions'' (journal), a chemistry journal published by MDPI

Physics and chemistry

Biology and medicine

Psychology

Politics and culture

Proper names and titles

See also