寿命的意思是一个生物个体从诞生到死亡所经过的时间，一般将其单位定为“岁”，其值与年相同。寿命的原意不同于年龄，但由于语言上的错误导致有时候年龄可以代替寿命一词。英文的Longevity在人口学中往往等同于预期寿命。

长寿不仅是科学家们讨论的话题，同时也是科幻作品、乌托邦小说的主题。由于存在出生统计的不确和不完整，有时很难确定史上的最年长者。小说、传奇和民间故事都有描写超过现代标准下的人瑞寿命的例子。

此外，寿命一词也常用来表示一部机械、设备、设备或零件从开始使用到故障无法使用的时间长短。

The word "longevity" is sometimes used as a synonym for "life expectancy" in demography - however, the term "longevity" is sometimes meant to refer only to especially long-lived members of a population, whereas "life expectancy" is always defined statistically as the average number of years remaining at a given age. For example, a population's life expectancy at birth is the same as the average age at death for all people born in the same year (in the case of cohorts). Longevity is best thought of as a term for general audiences meaning 'typical length of life' and specific statistical definitions should be clarified when necessary.