発はつ育いく盛ざかり

Meanings

1

period of rapid growth; growth spurt

Refers to a stage of life, especially childhood or adolescence, when physical development is most pronounced.

彼かれは発はつ育いく盛ざかりで、毎まい日にちたくさん食たべる。
He is in a period of rapid growth and eats a lot every day.