React (verb)

1. To respond or behave in a particular way in response to a stimulus or situation.
2. To act in opposition to something.
3. To show a reaction to something.

Origin:

From latin re- "back" + agere "to do, act".

Examples:

1. He reacted angrily to the news.
2. She reacted to the stimulus quickly.
3. They reacted to the change with resistance.
4. The crowd reacted to the announcement with applause.
5. The company reacted to the crisis with a plan.