thymus

American  

[thahy-muhs] / ˈθaɪ məs /

noun

Anatomy.

plural

thymuses, thymi

1. a ductless, butterfly-shaped gland lying at the base of the neck, formed mostly of lymphatic tissue and aiding in the production of T cells of the immune system: after puberty, the lymphatic tissue gradually degenerates.

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thymus British  

/ ˈθaɪməs /

noun

1. a glandular organ of vertebrates, consisting in man of two lobes situated below the thyroid. In early life it produces lymphocytes and is thought to influence certain immunological responses. It atrophies with age and is almost nonexistent in the adult

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thymus Scientific  

/ thī′məs /

1. An organ of the lymphatic system located behind the upper sternum (breastbone). T cells (T lymphocytes) develop and mature in the thymus before entering the circulation. In humans, the thymus stops growing in early childhood and gradually shrinks in size through adulthood, resulting in a gradual decline in immune system function.

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Etymology

Origin of thymus

1685–95; < New Latin < Greek thýmos warty excrescence, thymus

Example Sentences

By about age 75, the thymus is essentially nonfunctional.

From Science Daily • Dec. 29, 2025

Other researchers are investigating whether transplanted stem cells could help regrow functional thymus tissue.

From Science Daily • Dec. 29, 2025

Sakaguchi then isolated mature T-cells from genetically identical mice and injected them into the mice without a thymus, and that appeared to protect them.

From The Wall Street Journal • Oct. 6, 2025

In December 2020, UK researchers UCL and the Francis Crick Institute rebuilt a human thymus - an essential organ in the immune system - using human stem cells and a bioengineered scaffold.

From BBC • Sep. 4, 2025

Concentric corpuscles, like those of the thymus, have been recorded in it.

From Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 8 "Dubner" to "Dyeing" by Various