overactive

adjective

over·​ac·​tive ˌō-vər-ˈak-tiv 

: excessively or abnormally active

overactive glands

an overactive imagination

overactivity

ˌō-vər-ak-ˈti-və-tē 

noun

Synonyms

• heated
• excited
• agitated
• hyperactive

Examples of overactive in a Sentence

She has an overactive bladder.

His crazy ideas are products of an overactive imagination.

Recent Examples on the Web

Treg cells also control internal revolt in the form of an overactive immune response by other immune cells that can trigger allergies and autoimmune diseases such as arthritis, lupus and multiple sclerosis – diseases that develop when Treg cells are defective in either number, function or both. —Mitzi Nagarkatti, The Conversation, 10 Oct. 2025

An overactive immune system also contributes. —Daryl Austin, USA Today, 7 Oct. 2025

The hormone, hepcidin, can be slightly overactive when your iron levels go up. —Abby Norman, Verywell Health, 6 Oct. 2025

Since blemishes are closely tied to overactive oil glands, using a mask with these clays helps reduce one of the main triggers of acne. —Christa Joanna Lee, Allure, 30 Sep. 2025

Word History

First Known Use

1647, in the meaning defined above

Rhymes for overactive

• bioactive
• hyperactive
• interactive
• nonreactive
• psychoactive
• putrefactive
• retroactive
• unattractive
• unreactive
• vasoactive
• active
• tractive

Kids Definition

overactive

adjective

over·​ac·​tive ˌō-və-ˈrak-tiv 

: very active and especially abnormally so

an overactive thyroid

overactivity

-rak-ˈtiv-ət-ē 

noun

Medical Definition

overactive

adjective

over·​ac·​tive ˌō-və-ˈrak-tiv 

: excessively or abnormally active

an overactive mind

overactive glands

overactivity

-ˌrak-ˈtiv-ət-ē 

noun

plural overactivities