thymus

noun

thy·​mus ˈthī-məs 

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

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

Along with its kidney, the NYU pig, bred by United Therapeutics, also provided its thymus, an organ of the immune system. —Karen Weintraub, USA TODAY, 24 Apr. 2024

Scientists have grown mice containing cells from rat pancreases or thymuses, as well as rats that have pancreas or kidney cells from mice. —Will Sullivan, Smithsonian Magazine, 2 May 2024

Word History

Etymology

New Latin, from Greek thymos warty excrescence, thymus

First Known Use

1578, in the meaning defined above

Kids 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