nonage

noun

1. the period of legal minority, or of an age below 21.
2. any period of immaturity.

noun

1. law the state of being under any of various ages at which a person may legally enter into certain transactions, such as the making of binding contracts, marrying, etc
2. any period of immaturity

n.late 14c., “state of not being of age,” from Old French nonage, from non- (see non-) + age (see age (n.)).