IPA: //ˈkwɔːrtərli//
KK: /ˈkwɔrtərli/
Happening or published every three months.
The company releases its financial report on a quarterly basis.
Occurring every three months or four times a year.
The company holds quarterly meetings to discuss progress and plans.
A publication or report that is released four times a year, typically every three months.
The company released its quarterly report to update investors on its financial performance.
Quarterly → It is formed from "quarter" (from Old French *quartier*, meaning a fourth part) and "-ly" (meaning in a manner of). The word "quarterly" refers to something that occurs in the manner of a fourth part of a year, specifically every three months.
Think of a 'fourth part' ('quarter') of the year happening 'in a manner of' ('-ly') — that's why quarterly means something that happens every three months.