reactive

adjective

re·​ac·​tive rē-ˈak-tiv 

1

: of, relating to, or marked by reaction or reactance

2

a

: readily responsive to a stimulus

b

: occurring as a result of stress or emotional upset

reactive depression

reactively adverb

reactiveness noun

Examples of reactive in a Sentence

The government's response to the problem was reactive rather than proactive.

Recent Examples on the Web

The convergence of an expanding threat surface and rapidly advancing attacker capabilities makes a reactive cybersecurity strategy untenable. —Shane Buckley, Forbes.com, 30 June 2025

Chris Whipple, an expert on White House chiefs of staff, said Trump is reactive and instinctive, which drove his success on the campaign trail. —Tamara Keith, NPR, 28 June 2025

On the other hand, a reactive result means that the test showed a reaction, suggesting the presence of HIV antigens or antibodies in your sample. —Suchandrima Bhowmik, Health, 28 June 2025

While other blood group systems exist, their antigens are less reactive and are generally screened only if a patient shows rare or unexpected antibodies. —Jenny Lehmann, Discover Magazine, 26 June 2025

Word History

First Known Use

1717, in the meaning defined at sense 1

Phrases Containing reactive

• C-reactive protein
• hyper-reactive
• reactive arthritis

Rhymes for reactive

• attractive
• contractive
• extractive
• inactive
• proactive
• refractive
• subtractive
• active
• tractive
• bioactive
• hyperactive
• interactive

Kids Definition

reactive

adjective

re·​ac·​tive rē-ˈak-tiv 

1

: of or relating to reaction

2

: reacting or tending to react

reactively adverb

reactiveness noun

reactivity

(ˌ)rē-ˌak-ˈtiv-ət-ē 

noun

Medical Definition

reactive

adjective

re·​ac·​tive rē-ˈak-tiv 

1

a

: of, relating to, or marked by reaction

reactive symptoms

a reactive process

b

: capable of reacting chemically

highly reactive materials

2

a

: readily responsive to a stimulus

the skin of the geriatric is less reactive than that of younger persons

—Louis Tuft

b

: occurring as a result of stress or emotional upset especially from factors outside the organism

reactive depression