IPA: /dɪsˈpɜːrsɪvli/
KK: /dɪsˈpɜːrsɪvli/
In a manner that spreads out or scatters over a wide area.
The light traveled dispersively through the prism, creating a spectrum of colors.
Dispersively → It is formed from "dis-" (meaning apart) and "persus" (from Latin "perspere", meaning to scatter). The word "dispersively" means in a manner that scatters or spreads apart.
Think of something that spreads 'apart' ('dis-') and 'scatters' ('perspere') — that's why dispersively means in a way that scatters.