reaction

/riˈækʃən/
noun
  1. A response or behavior that shows how someone feels about something that happens.
    • His immediate reaction to the joke was a loud laugh.
    • The crowd's reaction to the goal was pure excitement.
    • She had a strong reaction to the movie's ending.
  2. A chemical process in which substances change into different substances.
    • Scientists studied the reaction to develop a new medicine.
    • Photosynthesis is a chemical reaction that plants use to make food.
    • The reaction between acid and metal produces hydrogen gas.
  3. A physical response of the body to something such as a drug, food, or allergen.
    • The vaccine may cause a mild reaction like soreness at the injection site.
    • He had an allergic reaction to peanuts and needed medicine.
    • Her reaction to the cold weather was shivering.
  4. A change in opinion or behavior that opposes a previous trend or movement.
    • There was a public reaction against the new law within days.
    • The fashion world saw a reaction to minimalism with bold colors.
    • The election results were a reaction against the current policies.
Antonyms