Of a child, etc.: not fully grown or developed; young. Also of a sibling: younger.

Not come to puberty or maturity; immature.

= impuberal, adj.

= impuberal, adj. Also absol. as n.

the stage of life during which children receive primary education, typically (in the United Kingdom) between the ages of about five and eleven…

Education. Designating a school, pupil, or educational system of the first or elementary level; of or relating to primary education.

Of a child: having nearly reached the beginning of adolescence.

Almost adolescent; = preadolescent, adj.

Of a child: under (esp. just under) thirteen years old; not yet teenage, subteen.

(in the context of beginning school) children approaching the age of five considered collectively; also occasionally in singular.