also: ギャングエージ
noun
gang age; preadolescence
A developmental stage, roughly ages 8–12, when children form close peer groups and may engage in group mischief or minor delinquency. Used in psychology and education contexts.
ギャングエイジの子どもたちは、仲間との絆をとても大切にする。
Children in the gang age stage place great importance on bonds with their peers.
この時期はギャングエイジとも呼ばれ、集団で行動することが増える。
This period is also called the gang age, and group activities become more frequent.
思春期 refers to puberty and adolescence (roughly ages 12–18), while ギャングエイジ is the earlier preadolescent phase focused on peer group formation.
Loanword from English 'gang age', a term used in developmental psychology.