reaction

B2 · Upper Intermediate Countable noun Science Technical

n. a process where two or more substances change into something new.

n. a process involving the rearrangement of the molecular or ionic structure of a substance.

Español:reacción

“The chemical reaction caused the liquid to turn bright green.”

“The catalyst was added to accelerate the reaction, ensuring that the compound reached stability before the temperature dropped.”

B1 · Intermediate Countable noun Computing Informal

n. an icon or emoji you use to show how you feel about a post on social media.

n. a digital feedback mechanism, typically an emoji, used to express a specific sentiment toward online content.

“She got over fifty heart reactions on her new photo.”

“The platform introduced several new reactions, allowing users to express nuanced emotions beyond a simple 'like' button.”

C1 · Advanced Uncountable noun Politics Academic · Formal

n. a movement that opposes social or political change.

n. opposition to political or social progress or reform; reactionary policy.

“The new law met with strong reaction from traditional groups.”

“The revolution was followed by a period of intense political reaction, as the old elite sought to dismantle the newly established democratic institutions.”