1) The segment at the end of each chromosome arm which consists of a series of repeated DNA sequences that regulate chromosomal replication at each cell division. Some of the telomere is lost each time a cell divides, and eventually, when the telomere is gone, the cell dies.

2) The natural end of a eukaryotic chromosome composed of a usually repetitive DNA sequence and serving to stabilize the chromosome.

3) A telomere is the end of a chromosome. Telomeres are made of repetitive sequences of non-coding DNA that protect the chromosome from damage. Each time a cell divides, the telomeres become shorter. Eventually, the telomeres become so short that the cell can no longer divide.