Antediluvian

Very old, old-fashioned, or out of date

Antiquated

Aged, old

Archaic

Ancient

Callow

Immaturely young, very young

Hoary

Gray/White with age, venerable, old

Immature

Juevenile, Childish

Ingenue

Innocent, Young

Jejune

Childish

Juvenescent

Young in appearance

Neophyte

Beginner or novice in life, young

Newfangled

New to, new

Novice

New to something

Precocious

Unusually Mature

Puerile

Pertaining to Childhood

Senescence

Growing old, aging

Senile

Getting weaker/older

Superannuated

Retired due to age

Tyro

Novice

Venerable

Great/Impressive Age

Veteran

Mature