To the Editor: We accept the premise of Oliver French, M.D., that the definition of very old age is far from an exact science. Like many other classificatory labels, determining which individuals fit the category and which do not is a relativistic matter. Neugarten (1) was among the first to differentiate between specific segments of the aging population, making the distinction between the "young-old" (55–74 years) and the "old-old" (75-plus years). More recently, authors have referred to individuals above 85 years as the "oldest-old" (2), and centenarians, those who are 100 years and older, have received some empirical attention (3). Thus, terms such as "old" or "very old" are not static entities. Their meanings vary across time and cultures. As the life expectancy continues to increase because of changes in medical technology and lifestyle behaviors (4), and with the advent of possible means to extend the human life span by means of chromosomal modification (5), the definition of very old age is likely to be altered in the near future.