nonage
Concise Oxford English Dictionary © 2008 Oxford University Press:
nonage /ˈnəʊnɪdʒ, ˈnɒn-/
▶noun formal the period of a person's immaturity or youth.
– origin ME: from OFr. nonage, from non- ‘non-’ + age ‘age’.
'nonage' also found in these Oxford entries:

