[ thahy-muhs ]
See synonyms for thymus on
noun,plural thy·mus·es, thy·mi [thahy-mahy]. /ˈθaɪ maɪ/. Anatomy.
  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.

Origin of thymus

1685–95; <New Latin <Greek thýmos warty excrescence, thymus
  • Also called thymus gland . Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use thymus in a sentence

British Dictionary definitions for thymus


/ (ˈθaɪməs) /

nounplural -muses or -mi (-maɪ)
  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

Origin of thymus

C17: from New Latin, from Greek thumos sweetbread

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

Scientific definitions for thymus


[ thīməs ]

  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.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.