IPA: /ˈfɔːrməli/
KK: /ˈfɔrməli/
In a way that follows established rules or customs, often in a serious or official manner.
The event was conducted formally, with all guests dressed in their best attire.
Formally → It is formed from "formal" (from Latin *formalis*, meaning pertaining to form) and "-ly" (meaning in a manner of). The word "formally" means in a manner that adheres to established forms or conventions.
Think of doing something in a way that follows established 'forms' — 'formal' relates to form, and '-ly' indicates the manner of doing it.