/ree akt"/ , v.i.
1. to act in response to an agent or influence: How did the audience react to the speech?
2. to act reciprocally upon each other, as two things.
3. to act in a reverse direction or manner, esp. so as to return to a prior condition.
4. to act in opposition, as against some force.
5. to respond to a stimulus in a particular manner: reacting to a shock by jumping; to react to the word "coward" with anger.
6. to undergo a chemical reaction.
[ 1635-45; RE- + ACT, prob. modeled on ML reagere ]