Synonyms

thymus

American

[thahy-muhs] / ˈθaɪ məs /

noun

Anatomy.

plural

thymuses, thymi

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.

thymus British

/ ˈθaɪməs /

noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

thymus Scientific

/ thī′məs /

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.

Etymology

Origin of thymus

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

Vocabulary lists containing thymus

Human Anatomy and Physiology - High School

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

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

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

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

Surgical Anatomy—Malformations:Cervical auricles;Thyreo-glossal cysts and fistulæ;Lateral fistula—Cervical ribs—Wry-neck:Varieties;Cicatricial contraction—Injuries:Contusions—Fractures of hyoid, larynx, etc.:Cut-throat—Infective conditions:Diffuse cellulitis;Actinomycosis;Boils and Carbuncles—Tumours:Cystic:Branchial cysts;Cystic lymphangioma;Blood cysts;Bursal cysts—Solid:Lipoma;Fibroma;Osteoma;Sarcoma;Carcinoma—The thymus gland—The carotid gland.

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

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023