The opposite of "the under-10s"?

[Ouisch]

In AmE, we usually refer to 11 and 12-year-olds as "pre-teens." In recent years the media has started referring to kids aged 10 to 12 as "tweens" - a slang term to describe that they are "between" being a child and a teenager. So, in summary, we basically classify children as either infants (babies), toddlers (one and two-year-olds), pre-schoolers (three and four-year-olds), various names for five to nine-year-olds, including "under 10s", pre-teens (or adolescents) and teenagers.

[Mehrgan]

In AmE, we usually refer to 11 and 12-year-olds as "pre-teens." In recent years the media has started referring to kids aged 10 to 12 as "tweens" - a slang term to describe that they are "between" being a child and a teenager. So, in summary, we basically classify children as either infants (babies), toddlers (one and two-year-olds), pre-schoolers (three and four-year-olds), various names for five to nine-year-olds, including "under 10s", pre-teens (or adolescents) and teenagers.

Thank you so much for the reply dear Ouisch.
Cheers!