IPA: /ˈræpɪdli/
KK: /ˈræpɪdli/
In a way that is fast or quick.
The train moved rapidly through the countryside.
Rapidly → It is formed from "rapid" (from Latin "rapidus", meaning to seize or snatch) and "-ly" (a suffix meaning in a manner of). The word "rapidly" means in a manner that seizes or occurs quickly.
Think of something that happens quickly, as if it 'seizes' your attention — that's why 'rapidly' means to do something in a quick manner.