cell line

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A cell culture that is derived from one cell or set of cells of the same type and in which under certain conditions the cells proliferate indefinitely in the laboratory.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun genetics A biological tissue or group of individual cells that are genetically identical as a result of dividing mitotically from a single progenitor cell.