mid-teen

[ mid-teen ]
/ ˈmɪdˈtin /

adjective

of, relating to, or characteristic of a person 15–17 years old: specializing in mid-teen clothes.

noun

a person 15–17 years old: an ad campaign aimed at mid-teens.
mid-teens, numbers, amounts, ages, etc., midway between 13 and 19: He started at a salary in the mid-teens.