IPA: /ˈdaʊn.wɚd.li/
KK: /ˈdaʊnˌwɜrdli/
In a direction that goes down or towards a lower place.
The bird flew downwardly from the tree branch.
Downwardly → It is formed from "downward" (from Old English "dūnweard", meaning toward the bottom) and the suffix "-ly" (meaning in a manner of). The word "downwardly" means in a manner that is directed toward the bottom or lower position.
Think of moving 'toward the bottom' ('downward') and the '-ly' just means in that manner. So, downwardly describes how something is directed down.