HOW OLD [C, U] › the number of years that someone has lived, or that something has existed: The show appeals to people of all ages. She left India at the age of 12. Children under 10 years of age must be accompanied by an adult. She's about your age (= the same age as you). HISTORY [C] › a period of history: the Ice Age We're living in the age of electronic communication. OLD [U] › when something is old: Some wines improve with age.