noun
Formal, somewhat clinical term for the period when sexual maturity begins. Often used in medical or educational contexts.
春機発動期には、心身ともに大きな変化が起こる。
During puberty, significant changes occur both mentally and physically.
More common and general term for adolescence/puberty. 春機発動期 is more formal and specifically emphasizes the onset of sexual maturity.
Compound of 春機 (sexual awakening) + 発動 (activation) + 期 (period). The exact historical derivation is uncertain; the spelling is conventionally associated with the onset of puberty.