underactive
adjective
un·der·ac·tive
ˌən-dər-ˈak-tiv 
: characterized by an abnormally low level of activity
an underactive thyroid gland
Examples of underactive in a Sentence
Recent Examples on the Web
Hypothyroidism is an underactive thyroid gland, and hyperthyroidism is an overactive thyroid gland.
—
Colleen Doherty, Verywell Health, 18 Dec. 2025
In people with depression, this area is underactive.
—Emily Kay Votruba, EverydayHealth.com, 15 Dec. 2025
Based on these three levels, a doctor can determine whether the thyroid is underactive or overactive.
—Melissa Rudy, FOXNews.com, 8 Dec. 2025
This is important because hair loss can often be a sign of thyroid problems; both an underactive and an overactive thyroid can disrupt hair growth, resulting in hair thinning or shedding.
—Varsha Patel, Refinery29, 21 Aug. 2025
See All Example Sentences for underactive
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Colleen Doherty, Verywell Health, 18 Dec. 2025
In people with depression, this area is underactive.
—Emily Kay Votruba, EverydayHealth.com, 15 Dec. 2025
Based on these three levels, a doctor can determine whether the thyroid is underactive or overactive.
—Melissa Rudy, FOXNews.com, 8 Dec. 2025
This is important because hair loss can often be a sign of thyroid problems; both an underactive and an overactive thyroid can disrupt hair growth, resulting in hair thinning or shedding.
—Varsha Patel, Refinery29, 21 Aug. 2025
See All Example Sentences for underactive
Cite this Entry
“Underactive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/underactive. Accessed 24 Dec. 2025.
Copy CitationKids Definition
underactive
adjective
un·der·ac·tive
ˌən-də-ˈrak-tiv
: having an abnormally low level of activity
an underactive gland
Medical Definition
underactive
adjective
un·der·ac·tive
-ˈak-tiv
: characterized by an abnormally low level of activity
an underactive thyroid gland
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