overactive

adjective

over·​ac·​tive ˌō-vər-ˈak-tiv How to pronounce overactive (audio)
: excessively or abnormally active
overactive glands
an overactive imagination
overactivity noun

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Our amygdala is overactive, our nervous systems are fried and our dopamine cycles are hijacked by short-term stimuli. Chris Schembra, Rolling Stone, 22 Oct. 2025 Typically, the immune-stimulating tactics employed in the past have either done too little to activate the immune system or done too much, triggering an overactive response that can damage the body. Kaitlin Sullivan, NBC news, 19 Oct. 2025 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 See All Example Sentences for overactive

Word History

First Known Use

1647, in the meaning defined above

Time Traveler
The first known use of overactive was in 1647

Browse Nearby Words

Cite this Entry

“Overactive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/overactive. Accessed 24 Oct. 2025.

Kids Definition

overactive

adjective
over·​ac·​tive ˌō-və-ˈrak-tiv How to pronounce overactive (audio)
: very active and especially abnormally so
an overactive thyroid
overactivity noun

Medical Definition

overactive

adjective
over·​ac·​tive ˌō-və-ˈrak-tiv How to pronounce overactive (audio)
: excessively or abnormally active
an overactive mind
overactive glands
overactivity noun
plural overactivities

More from Merriam-Webster on overactive

Last Updated: - Updated example sentences
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