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

This marks the transition from reactive cybersecurity to adaptive cyber resilience. — Aliasgar Dohadwala, Forbes.com, 7 Aug. 2026

That could have made playing a highly reactive character like Carol therapeutic. — Glenn Whipp, Los Angeles Times, 6 Aug. 2026

The protein sends electrons flowing in the opposite direction of their usual microscopic relay race, a reversal that generates reactive oxygen species, cellular stress, and inflammation. — Jonathan Wosen, STAT, 6 Aug. 2026

The Turtle-on-Moon Back Bling and Addison’s Sundae Back Bling can also be purchased, along with the Fame Scepter Pickaxe and the reactive Addison’s Biggest Fan Pickaxe. — Tanya Fedak, Variety, 5 Aug. 2026

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

• active
• tractive
• attractive
• contractive
• extractive
• inactive
• proactive
• refractive
• subtractive
• 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