Lymphoid Organ Where T Cells Mature

Word Meaning:

THYMUS — (anatomy, immunology) Ellipsis of thymus gland (“A ductless gland, consisting mainly of lymphatic tissue, located behind the top of the breastbone. It is most active during puberty, after which it shrinks in size. It plays an important role in the development of the immune system and produces lymphocytes.”).

Definitions from Wiktionary.