(a) adj. that has been in existence for a year; (b) n. an animal or (subsequently) a child that has been alive for one year.

(a) adj. that is seven years of age; (b) n. a child, animal, or thing that is seven years of age.

(a) adj. that is seventeen years of age; (b) n. a person, animal, or thing that is seventeen years of age.

(a) n. a child of nine years of age; (b) adj. that is nine years of age.

Of, relating to, or characteristic of a centenarian or centenarians.

Of a person: (looking) approximately twenty years old.

an undetermined age between thirty and forty; spec. applied to members of the ‘baby boom’ generation entering their thirties in the mid-1980s; also…