English definition of “react”
/riˈækt/ verb [I]
SAY/DO › to say, do, or feel something because of something else that has been said or done: He reacted angrily to her comments.
BAD EFFECT › to become ill because something that you have eaten or used on your body has had a bad effect on you: My skin reacts to most perfumes.
SUBSTANCES › In science, if a substance reacts with another substance, it changes: Carbon reacts with oxygen to produce carbon dioxide.