IPA: /kwɒˈdrʌpli/
KK: /kwɑːˈdrʌpli/
In a manner that involves four times or in four different ways.
The team worked quadruply hard to meet the deadline.
Quadruply → It is formed from "quadra-" (from Latin "quadrus", meaning four) and "-ply" (from Old English "plygan", meaning to fold or multiply). The word "quadruply" means to multiply by four or to do something four times.
Think of 'four' ('quadra-') being 'multiplied' ('-ply') — that's why quadruply means to do something four times.
No commonly confused words.