variants
or thymus gland
plural thymuses also thymi
ˈthī-ˌmī 
: a glandular structure of largely lymphoid tissue that functions especially in cell-mediated immunity by being the site where T cells develop, is present in the young of most vertebrates typically in the upper anterior chest or at the base of the neck, and gradually decreases in size and activity after puberty
Examples of thymus in a Sentence
Recent Examples on the Web
In 1989, Hale was diagnosed with cancer of the thymus.
—
Colson Thayer, People.com, 20 Jan. 2025
The addition of the thymus, a small organ in the upper chest that’s part of the immune system, was meant to help prevent rejection.
—Emily Mullin, WIRED, 17 Dec. 2024
The thymus, which produces infection-fighting T cells, reaches its peak size at puberty and then steadily shrinks.
—Lisa M. Krieger, The Mercury News, 29 Oct. 2024
Adding the pig's thymus, Montgomery said, should protect the pig kidney from being attacked by the human immune system.
—Karen Weintraub, USA TODAY, 24 Apr. 2024
See All Example Sentences for thymus
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Colson Thayer, People.com, 20 Jan. 2025
The addition of the thymus, a small organ in the upper chest that’s part of the immune system, was meant to help prevent rejection.
—Emily Mullin, WIRED, 17 Dec. 2024
The thymus, which produces infection-fighting T cells, reaches its peak size at puberty and then steadily shrinks.
—Lisa M. Krieger, The Mercury News, 29 Oct. 2024
Adding the pig's thymus, Montgomery said, should protect the pig kidney from being attacked by the human immune system.
—Karen Weintraub, USA TODAY, 24 Apr. 2024
See All Example Sentences for thymus
Cite this Entry
“Thymus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/thymus. Accessed 27 Feb. 2025.
Copy CitationKids Definition
thymus
noun
thy·mus
ˈthī-məs
plural thymuses also thymi
-ˌmī
: a gland that is found in the young of most vertebrates usually in the chest near the heart, that before and for a time after birth has very important effects on the production and development of T cells, and that becomes less active and gradually shrinks or disappears with age
Medical Definition
thymus
noun
thy·mus
ˈthī-məs
variants
or thymus gland
plural thymuses also thymi
-ˌmī
: a glandular structure of largely lymphoid tissue that functions in cell-mediated immunity by being the site where T cells develop, that is present in the young of most vertebrates typically in the upper anterior chest or at the base of the neck, that arises from the epithelium of one or more embryonic branchial clefts, and that gradually decreases in size and activity after puberty
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