|—n , pl -muses, -mi|
|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|
|[C17: from New Latin, from Greek thumos sweetbread]|
thymus thy·mus (thī'məs)
n. pl. thy·mus·es
A lymphoid organ that is located in the superior mediastinum and lower part of the neck and is necessary in early life for the normal development of immunological function.
The thymus of a calf or lamb.
|thymus (thī'məs) Pronunciation Key
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.