(anthropology) An established social category or group consisting of people born during a certain time span who together move through a series of culturally defined age grades.

(anthropology) An organized, culturally defined social category of people with membership based on age; in some societies it is entered automatically when one reaches a certain age, while in others it is entered through an initiation rite and/or the payment of a fee.

(demography) The age that divides a population (of a country etc.) into two numerically equivalent groups.

plural of age identity

(psychology) The age category such as "child", "young adult", "old person", etc. that is part of a person's self-identity.

(archaeology, paleontology, geology, geochronology) The age of a material as determined by radiometric dating.

present participle of age out

(historical) A period that lasted from the mid-16th (or mid-15th) to the mid-19th centuries, in which the dominance of sailing ships in global trade and warfare culminated.

Alternative letter-case form of space age

A modern spiritual and religious movement. / (music) Ellipsis of New Age music..