The time period of a human being's majority; the time during which a human being has reached physical maturity, and ending with its death.
The state or condition of a human being once it has reached physical maturity, and is presumed to have reached a state of psychological maturity, to wit: once it has become an adult.
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.