noun
teens; teenage; ages 10-19
Refers to the age range from 10 to 19, or to people in that age group. Commonly used in demographic and social contexts.
このアンケートは十代の若者を対象にしている。
This survey targets teenagers.
彼女はまだ十代なのに、とても落ち着いている。
Even though she is still in her teens, she is very composed.
noun
tenth generation
Refers to the tenth generation of a family, dynasty, or lineage. Less common in everyday conversation; more often seen in historical or genealogical contexts.
See also: 代
彼は十代目の当主として家を守っている。
He is protecting the family as the tenth-generation head.