The period between childhood and adolescence, between the ages of about 9 and 11 for girls, and 10 and 12 for boys.
The time of life between thirteen and nineteen years old; the teenage years.
The second decade of a century: the 1910s, 2010s, etc. The oneties, the tens.
The numbers between thirteen and nineteen.
The range between 10 and 19.