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

See Examples For:

thymus thymuses

According to the researchers, these findings highlight a potentially important but previously underrecognized role for the thymus in determining how effectively modern cancer immunotherapies work.

From Science Daily ● Jun. 1, 2026

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

But beginning in early adulthood, the thymus starts to shrink.

From Science Daily ● Dec. 29, 2025

They asked whether the body could be prompted to create a temporary "factory" that produces the same T cell stimulating signals typically made by the thymus.

From Science Daily ● Dec. 29, 2025

As the lower part of the thymus canal most often persists, an incomplete external fistula is the form most frequently met with.

From Manual of Surgery Volume Second: Extremities—Head—Neck. Sixth Edition. by Alexander Miles

Two new studies found that adults with healthier thymuses were more likely to live longer and less likely to develop serious diseases.

From Science Daily ● Jun. 1, 2026

The results showed that patients with healthier thymuses tended to respond better to treatment.

From Science Daily ● Jun. 1, 2026

From some newborn mice he cut out the pinhead-size thymuses.

From Time Magazine Archive

To cross-check his findings, Dr. Miller took some newborn mice, removed their thymuses, and a week later grafted in new thymuses from mice of a different strain.

From Time Magazine Archive