reaction

The word “reaction” means a response, in words, feelings, or actions, to something that has happened. In plain terms, a response to an event — emotional, chemical, or political depending on context.

“Reaction” is pronounced ree-AK-shuhn (/ɹiˈækʃən/ in IPA).

Here is “reaction” used in a sentence: “His first reaction was disbelief.”

Words with a similar meaning to “reaction” include reax and rxn.

“Reaction” is a noun.

The word “reaction” comes from Latin. From Latin reactio, built from re- ("again") and agere ("to do, to act").

“Reaction” is a fairly common word in modern English, usually learned at around the B2 level.

“Reaction” has 3 distinct senses listed in this dictionary. The most common is: a response, in words, feelings, or actions, to something that has happened.

A reaction is immediate and instinctive — it happens almost automatically, often driven by emotion, before you have time to think. A response is more considered and deliberate, chosen after reflection. Snapping back in anger is a reaction; pausing and replying calmly is a response. The difference is largely one of control.

In everyday use, reactions can be emotional, such as fear or delight, verbal, such as a comment or reply, or physical, such as flinching or applauding. The word also has specialised senses — a chemical reaction between substances, or an allergic reaction in the body — but all share the idea of a response to something that has happened.

If someone shares surprising news and you gasp, that gasp is your reaction. Laughing at a joke, jumping at a loud bang, or firing off an angry reply are all reactions — each one an immediate response in feeling, words, or action to something that has just happened.