react

 
Pronunciation: /rɪˈakt/

verb

[no object]
  • 1act in response to something; respond in a particular way: he reacted angrily to the news of his dismissal the market reacted by falling a further 3.1%
  • (react against) respond with hostility or a contrary course of action to: they reacted against the elite art music of their time
  • suffer from adverse physiological effects after ingesting, breathing, or touching a substance: many babies react to soy-based formulas
  • Stock Exchange (of share prices) fall after rising: the shares reacted to 222p before rallying to 228p
  • 2 Chemistry & Physics interact and undergo a chemical or physical change: the sulphur in the coal reacts with the limestone during combustion
  • [with object] cause (a substance) to undergo a chemical or physical change by interacting with another substance: in the new process the ammonia will be reacted with oxygen

Origin:

mid 17th century: from re- (expressing intensive force or reversal) + act, originally suggested by medieval Latin react- 'done again', from the verb reagere