subperiod

noun

sub·​pe·​ri·​od ˈsəb-ˌpir-ē-əd 

variants or sub-period

plural subperiods or sub-periods

: a period that is a subdivision of a longer period

… the Ice Age, more precisely, 10,000 years ago or the tail end of the Pleistocene subperiod.

—Robert Carr

Let's look at the subperiods of the 1980s. The first quarter of the decade had to be devoted to fighting against two-digit inflation.

—The Christian Science Monitor

Word History

First Known Use

1843, in the meaning defined above