overactive
adjective
over·ac·tive
ˌō-vər-ˈak-tiv 
: excessively or abnormally active
overactive glands
an overactive imagination
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
Much of the onscreen conflict involves Colin’s parents, who, unlike their literary counterparts, know that their son is gay and take an embarrassingly overactive role in nurturing his love life.
—
Justin Chang, New Yorker, 30 Jan. 2026
Whether due to genetics, autoimmune issues, or other factors, people with C3G have an overactive complement system (which is part of the immune system).
—Carrie Madormo, Health, 30 Jan. 2026
Melasma is triggered by hormonal shifts after birth, especially changes in estrogen, which can keep pigment-producing cells overactive even after delivery.
—Alex Vance, Parents, 29 Jan. 2026
In contrast, pathogenic inflammation can stem from overactive immune cells releasing inflammatory signals after a prolonged response to a bacteria or virus.
—Allison Aubrey, NPR, 19 Jan. 2026
See All Example Sentences for overactive
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Justin Chang, New Yorker, 30 Jan. 2026
Whether due to genetics, autoimmune issues, or other factors, people with C3G have an overactive complement system (which is part of the immune system).
—Carrie Madormo, Health, 30 Jan. 2026
Melasma is triggered by hormonal shifts after birth, especially changes in estrogen, which can keep pigment-producing cells overactive even after delivery.
—Alex Vance, Parents, 29 Jan. 2026
In contrast, pathogenic inflammation can stem from overactive immune cells releasing inflammatory signals after a prolonged response to a bacteria or virus.
—Allison Aubrey, NPR, 19 Jan. 2026
See All Example Sentences for overactive
Cite this Entry
“Overactive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/overactive. Accessed 3 Feb. 2026.
Copy CitationKids Definition
overactive
adjective
over·ac·tive
ˌō-və-ˈrak-tiv
: very active and especially abnormally so
an overactive thyroid
Medical Definition
overactive
adjective
over·ac·tive
ˌō-və-ˈrak-tiv
: excessively or abnormally active
an overactive mind
overactive glands
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