• A type of immune cell that is made in the bone marrow and is found in the blood and in lymph tissue. The two main types of lymphocytes are B lymphocytes and T lymphocytes. B lymphocytes make antibodies, and T lymphocytes help kill tumor cells and help control immune responses. A lymphocyte is a type of white blood cell.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• A type of white blood cell that can recognize foreign substances in the body.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each); those with characteristics of neither major class are called null cells.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• Lymphocyte, type of white blood cell (leukocyte) that is of fundamental importance in the immune system because lymphocytes are the cells that determine the specificity of the immune response to infectious microorganisms and other foreign substances. In human adults lymphocytes make up roughly 20...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2020