re‧ac‧tive AC /riˈæktɪv/ adjective
[Word Family: noun: reaction, reactor, reactionary, overreaction; verb: react, overreact; adjective: reactionary, reactive]

1. reacting to events or situations rather than starting or doing new things yourself:
a reactive foreign policy

2. technical a reactive substance changes when it is mixed with another substance:
a highly reactive chemical

[TahlilGaran] Dictionary of Contemporary English ▲