|1.||[ verb ] show a response or a reaction to something|
|Related terms:||act refuse accept accept answer wonder explode greet notice respond stool answer treat overreact accept refuse reaction respondent|
|2.||[ verb ] act against or in opposition to|
"She reacts negatively to everything I say"
|Related terms:||act pursue buck backfire adversary|
|3.||[ verb ] (chemistry) undergo a chemical reaction; react with another substance under certain conditions|
"The hydrogen and the oxygen react"
|Related terms:||change_state bromate chemistry|