Definition of "senescent" [se•nes•cent]

• Growing old; aging. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Using a complex “systems biology” approach, the researchers, in conjunction with scientists from the University of Ulm in Germany, had set out to discover why cells become senescent, or, in other words, grow old."
• "Scientists are closing in on the mechanism of what are called "senescent cells," which cause the tissue deterioration responsible for aging."
• "Reporting in the journal Nature, researchers from the Mayo Clinic have found a way to clear away what are called senescent cells, which are cells that have stopped dividing and build up as people and animals age. senescent cells are so bad for the body:"