reaction
/ɹiˈækʃən/
A reaction is a reflexive or automatic response triggered by an external force or event. It implies a causal link where the 'reaction' is secondary to an initial 'action' or stimulus. In social contexts, it often describes an emotional or behavioral outburst. While a 'response' can be considered, planned, and measured, a 'reaction' frequently suggests something more immediate, instinctive, or visceral. In scientific contexts (chemistry and physics), the term is neutral and technical, describing the transformation of matter or the mechanical push-back of physical forces. Here, it lacks the emotional volatility found in human behavioral descriptions.
Countable when referring to specific responses from people ('The reactions were mixed') or a particular chemical process ('a combustion reaction'). Uncountable when discussing the general physical principle of force in physics ('the law of action and reaction').
💬Casual Conversation
KAREN I POSTED THAT PHOTO OF LEO. WHAT WAS THE REACTION?
None, because I already scrubbed it from the feed.
Meanings
Collocations & Compounds
chain reaction
Noun collocation: a series of events where each triggers the next
The sudden bank failure triggered a chain reaction of economic collapses.
allergic reaction
Noun collocation: a physical response by the immune system to a foreign substance
He had a severe allergic reaction after eating peanuts.
chemical reaction
Noun collocation: a process where substances transform into new products
The mixture produced a violent chemical reaction when the acid was added.
visceral reaction
Noun collocation: an instinctive, deep emotional response
Her visceral reaction to the news was one of pure shock.
trigger a reaction
Verb collocation: to cause a specific response to occur
The sudden noise was enough to trigger a reaction from the sleeping dog.