Century

A century was a period of time equal to one hundred years.

When the Fourth Doctor got his age confused between 736 and 739, Romana I, who herself was "nearly" 140, observed that counting one's age would get a "little bit foggy" after the first few centuries. (TV: The Ribos Operation)

Demonstrating the TARDIS to Rose Tyler, the Ninth Doctor first took her a hundred years from 2005 in the 21st century to 2105 in the 22nd century. (TV: Rose)