Reaction

How to spell reaction

8 letters · 3 syllables

How to pronounce reaction

Say the part in capitals loudest.

What does reaction mean?

1. nounA response or feeling produced by an event, situation, or piece of information.
2. nounA process in which substances interact and change into different substances.

Reaction in a sentence

• Her first reaction to the news was relief.

• Mixing the two solutions triggered a violent reaction in the beaker.

• The manager gauged the team's reaction to the new schedule.

• The experiment measured the heat released during the reaction.

Where does reaction come from?

Language of origin: Latin

The word comes from the Latin reactio, a noun built from the verb reagere, meaning 'to act back' or 'to do again in response'. That verb joins the prefix re-, meaning 'back' or 'again', with agere, the great Latin verb meaning 'to do, to drive, or to set in motion', which also gives us words like 'act', 'agent', and 'agitate'. The term first gained ground in the seventeenth century among scientists and philosophers, who used it for the response of one body or force to another, an idea later made famous in Newton's law that every action has an equal and opposite reaction. From the laboratory it spread into chemistry for the process by which substances transform one another, and into everyday English for any response a person makes to an event. The spelling holds onto the visible 'act' inside it, which is a useful reminder that the tricky ending is simply '-tion' added to that familiar root.

How the word is built

• re- (back, again)
• act (from Latin agere: to do, drive)
• -ion (noun-forming suffix)