What is the real definition for youth?

Youth is the time of life when one is young, and often means the time between childhood and adulthood (maturity). It is also defined as "the appearance, freshness, vigor, spirit, etc., characteristic of one who is young".

A youth is a young person who has not yet reached adult hood and refers to the time period before he becomes an adult (maturity), usually between the age some say of 13-15 years, before you turn 18 years. Usually youth refers to a young boy. The term young people refers to both gender male and female.
The book "Questions Young people ask answers that work" for example some young people says “This book has been a wonderful asset to us in understanding our problems and in knowing how to deal with them. Thank you for your concern for our well-being.” Numerous young readers throughout the world agree.
For this book and others please go to jw.org for free downloads, publications or read online.