killer cell

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various large differentiated T cells that recognize and lyse target cells bearing a specific foreign antigen, usually by infection with a virus, and that also function in defense against cancer cells. Also called cytotoxic T cell, killer T cell.

WordNet 3.0

1. n. T cell with CD8 receptor that recognizes antigens on the surface of a virus-infected cell and binds to the infected cell and kill it