Definition from Wiktionary, the free dictionary
lymphocyte (plural lymphocytes)
- (cytology, immunology) A type of white blood cell or leukocyte that is divided into two principal groups and a null group; B-lymphocytes, which produce antibodies in the humoral immune response, T-lymphocytes, which participate in the cell-mediated immune response and the null group, which contains natural killer cells, cytotoxic cells that participate in the innate immune response.
- See also Wikisaurus:lymphocyte
Derived terms 
type of white blood cell
lymphocyte m (plural lymphocytes)