re ‧ ac ‧ tive AC /riˈæktɪv/ BrE AmE 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