The term 'youthful period' can be broken down into four distinct crossword solutions: BOYHOOD (7 letters), teens (5 letters), NONAGE (6 letters), and salad days (9 letters). BOYHOOD is a term used to describe the time in a young person's life between childhood and adulthood, usually between the ages of 10 and 14. Teens is a term used to describe the time in a young person's life between adolescence and adulthood, usually between the ages of 13 and 19. NONAGE is a term used to describe the time in a young person's life before they reach legal age, usually between the ages of 0 and 18. Salad days is a term used to describe the time in a young person's life when they are most energetic and enthusiastic, usually between the ages of 15 and 25. All of these terms together describe the youthful period of a person's life, which is typically considered to be between the ages of 0 and 25.