Thymus is a small organ located in the chest, near the heart. It plays a critical role in the development of the immune system. The thymus produces T-cells, which help fight infection and disease. Some synonyms for the word "thymus" include immune gland, lymphoid organ, and lymphatic gland. Another synonym for the thymus is thymopoietin, which is a hormone produced by the thymus that stimulates the development and maturation of T-cells. While the thymus may be a small organ, it is essential for maintaining a healthy immune system and fighting off infections and disease.