DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   react
       v 1: show a response or a reaction to something [syn: react,
            respond]
       2: act against or in opposition to; "She reacts negatively to
          everything I say" [syn: react, oppose]
       3: undergo a chemical reaction; react with another substance
          under certain conditions; "The hydrogen and the oxygen react"