1(formal) showing a reaction or response The police presented a reactive rather than preventive strategy against crime. compare proactive2(chemistry) tending to show chemical change when mixed with an [..]

1712, from react + -ive. Related: Reactively; reactiveness; reactivity.

Responsive to a geiven stimuli or situation..2. Describing emotions associated with an espisode. The emotions are secondary to the actual event and could be stess or upheaval in the life of the one ex [..]

(adj) participating readily in reactions(adj) reacting to a stimulus

Readily or easily able to undergo a chemical change (Lesson 9)

As applied to a chemical species, the term expresses a kinetic property. A species is said to be more reactive or to have a higher reactivity in some given context than some other (reference) species if it has a larger rate constant for a specified elementary reaction. The term has meaning only by reference to some explicitly stated or implicitly a [..]

A class of compounds which are normally unstable and readily undergo violent change, react violently with water, can produce toxic gases with water, or possess other similar properties. Reactivity is one characteristic that can make a waste hazardous.

Acting out in order to ward off or escape a stimulus, for example, other dogs or people. Reactive dogs may be more tense and worked up when separated from the stimulus by a barrier or a fence. Reactiv [..]

a serologic test that is reactive tells you that the antigen or antibody being tested for is present

When you're being reactive, you're defending and trying to answer your opponent's threats.

A class of compounds which are normally unstable and readily undergo violent change, react violently with water, can produce toxic gases with water, or possess other similar properties. Reactivity is [..]