thymus

American  

[thahy-muhs] / ˈθaɪ məs /

noun

Anatomy.

thymuses, plural thymi plural

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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Other Word Forms

Noun Inflected Forms

• thymi
  plural
• thymuses
  plural

Etymology

Origin of thymus

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

Example Sentences

The findings were published in two papers in the same issue of Nature and challenge decades of assumptions about the thymus.

From Science Daily • Jun. 1, 2026

As a result, the thymus has received relatively little attention in large population studies.

From Science Daily • Jun. 1, 2026

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

Like the thymus it is a ductless gland, abundantly supplied with blood-vessels, and possesses a vast number of small cavities, lined with cells and containing an insoluble jelly.

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