Biological Period Between Childhood and Adulthood

Puzzle 7 of Shiny Things Piece of Cake Pack

Question is: Biological Period Between Childhood and Adulthood

and the answer is: PUBERTY

Word Meaning:

PUBERTY — A developmental phase brought about by the action of hormones as part of the maturing process. For humans, there are three in total.

Definitions from Wiktionary.