Time Lords are extremely long-lived, routinely counting their ages in terms of centuries; the Second Doctor claimed in The War Games that Time Lords could live "practically forever, barring accidents". The series has suggested that Time Lords have a different concept of ageing from humans. In "The Stolen Earth", the Tenth Doctor refers to when who he thought was his original incarnation was a "kid" at 90 years old. However, within a specific incarnation, a Time Lord is able to age, albeit much more slowly than a human. The War Doctor and Eleventh Doctor, over the course of the Last Great Time War and the Battle of Trenzalore, respectively, are seen to age within their respective incarnations to what would appear to a human to be old age; both conflicts are suggested within the series to last hundreds if not thousands of Earth years.
Time Lords are extremely long-lived routinely counting their ages in terms of centuries; the Second Doctor claimed in The War Games that Time Lords could live "practically forever barring accidents" The series has suggested that Time Lords have a different concept of ageing from humans In "The Stolen Earth" the Tenth Doctor refers to when who he thought was his original incarnation was a "kid" at 90 years old However within a specific incarnation a Time Lord is able to age albeit much more slowly than a human The War Doctor and Eleventh Doctor over the course of the Last Great Time War and the Battle of Trenzalore respectively are seen to age within their respective incarnations to what would appear to a human to be old age; both conflicts are suggested within the series to last hundreds if not thousands of Earth years