IPA: /prɪˈvɛntɪvli/
KK: /prɪˈvɛntɪvli/
In a way that stops something from happening before it occurs.
The doctor recommended getting vaccinated preventively to avoid illness.
Preventively → It is formed from "prevent" (from Latin "praevenire", meaning to come before) and "-ively" (a suffix forming adverbs). The word "preventively" means in a manner that comes before to stop something from happening.
Think of doing something 'before' ('praevenire') to stop it from happening — that's what preventively means.