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

His colleagues had discovered that removing the thymus in mice shortly after birth resulted in their immune systems going haywire and the development of autoimmune diseases.

From The Wall Street Journal • Oct. 6, 2025

A similar study looked at the thymus – a small organ involved in training the immune system.

From BBC • Nov. 20, 2024

Plus a tweak: The donor pig’s thymus gland, which trains the immune system, was attached to the donated kidney in hopes that it would help Pisano’s body tolerate the new organ.

From Seattle Times • Apr. 24, 2024

The drawing was made from a dissection and, for the sake of simplicity, only the enteron, respiratory organs, heart, and thymus are shown.

From Development of the Digestive Canal of the American Alligator by Reese, C. M.