catalyst
part of speech
noun (a catalyst, catalysts)
meaning for a pupil
1) (science) A substance that makes a chemical reaction go faster without being used up itself. tree →
2) A person or event that makes a big change happen, or makes it happen sooner. tree →
sense in the lessons
In science lessons it is the substance that speeds up a reaction, like enzymes in your body that help digest food, or the catalytic converter in a car. In history and stories it is the event that sets off big changes — «the catalyst for the war». It tells the reader that something started or sped up a change. Phrases: «a catalyst for change», «acted as a catalyst».
examples
- Enzymes in your saliva act as catalysts to break down food. tree →
- A catalyst speeds up a reaction but is not used up. tree →
- In the experiment, the catalyst made the hydrogen peroxide fizz quickly. tree →
- The new teacher was a catalyst for change in our school. tree →
- The storm was the catalyst that made the town build a stronger sea wall. tree →
- Rosa Parks's brave act became a catalyst for the bus boycott. tree →
- Platinum is a catalyst in a car's exhaust system. tree →
note
Countable: a catalyst, catalysts. Say «KAT-uh-list». Adjective: catalytic (a catalytic converter). In science the key point: the catalyst is still there, unchanged, at the end of the reaction.
Trees and pragmatics
Every meaning and example of «catalyst» parsed by Mova, each sentence with its dependency tree and frames.