The part of the body's immune system that is important for the immune response and helps protect it from infection and foreign bodies. The part of the body's immune system that is important for the immune response and helps protect it from infection and foreign bodies.
The lymphatic system is part of the circulatory system and a vital part of the immune system, comprising a network of lymphatic vessels that carry a clear fluid called lymph (from Latin lympha meaning water) directionally towards the heart. The spleen and the thymus are also lymphoid organs of the immune system. The tonsils are lymphoid organs that are also associated with the digestive system. Lymphoid tissues contain lymphocytes, and also contain other types of cells for support. The mucosa-associated lymphoid tissue (MALT) (also called mucosa-associated lymphatic tissue) is a diffuse system of small concentrations of lymphoid tissue found in various sites of the body, such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eye, and skin.  Lymphocytes are concentrated in the lymph nodes. The spleen and the thymus are also lymphoid organs of the immune system. The tonsils are lymphoid organs that are also associated with the digestive system. Lymphoid tissues contain lymphocytes, and also contain other types of cells for support. A fluid called lymph, (lymph = clear fluid) flows in lymphatic vessels, lymphatic tissue and red bone marrow. Fluid filters out of capillaries and drains into lymphatic vessels to become lymph. The content of lymph is the same as interstitial fluid, the fluid around tissue cells.  Definition of LYMPHOID. 1. : of, relating to, or being tissue (as of the lymph nodes or thymus) containing lymphocytes. 2. : of, relating to, or resembling lymph. Medical Definition of LYMPHOID. 1. : of, relating to, or being tissue (as the lymph nodes or thymus) containing lymphocytes. lymphadenoid tissue tissue resembling that of lymph nodes, spleen, bone marrow, tonsils, and lymph vessels. lymphoid tissue a latticework of reticular tissue whose interspaces contain lymphocytes. mesenchymal tissue embryonic connective tissue composed of stellate cells and a ground substance of coagulable fluid. the lymphoid tissue of the body, collectively; it consists of the bone marrow, thymus, lymph nodes, spleen, and gut-associated lymphoid tissue (tonsils, Peyer's patches). lymphoid tissue. a lattice work of reticular tissue, the interspaces of which contain lymphocytes Definition of LYMPHATIC. 1. a: of, relating to, or produced by lymph, lymphoid tissue, or lymphocytes b: conveying lymph. 2. : lacking physical or mental energy: sluggish. — lym·phat·i·cal·ly \-ti-k(ə-)lē\ adverb. See lymphatic defined for kids. ADVERTISEMENT.  Lymphoid tissue: The part of the body's immune system that is important for the immune response and helps protect it from infection and foreign bodies. Lymphoid tissue is present throughout the body and includes the lymph nodes, spleen, tonsils, adenoids, and other structures. 
https://en.wikipedia.org/wiki/Lymphatic_system https://en.wikipedia.org/wiki/Mucosa-associated_lymphoid_tissue https://en.wikipedia.org/wiki/Lymphatic_system http://www.histology.leeds.ac.uk/lymphoid/prim_sec_lymp_tiss.php http://www.merriam-webster.com/dictionary/lymphoid http://medical-dictionary.thefreedictionary.com/lymphoid+tissue http://www.merriam-webster.com/dictionary/lymphatic http://www.medicinenet.com/script/main/art.asp?articlekey=4224
lymphoid tissue definition