Infants: <1
Children: 1-11 years or <7th grade
Teens: 12-17 or 7th-12th grade
Denarian: Someone age 10 to 19.
Vicenarian: Someone in his or her twenties.
Tricenarian: Someone in his or her thirties.
Quadragenarian: Someone in his or her forties.
Quinquagenarian: Someone in his or her fifties.
Sexagenarian: Someone in his or her sixties.
Septuagenarian: Someone in his or her seventies.
Octogenarian: Someone in his or her eighties.
Nonagenarian: Someone in his or her nineties.
Centenarian: Someone 100 or more.
Supercentenarian: Someone 110 years old or more (no upper limit).