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

Inside the thymus, immature T cells go through a checkpoint process that helps create a diverse set of T cells.

From Science Daily • Dec. 29, 2025

By about age 75, the thymus is essentially nonfunctional.

From Science Daily • Dec. 29, 2025

Researchers understood in the 1980s that T-cells mature in the thymus and undergo a test to eliminate cells that would latch on to our own tissues.

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

The thymus gland attains a considerable development in the embryo and shrinks away to the merest vestige in the adult.

From Man And His Ancestor A Study In Evolution by Morris, Charles