IPA: /ɪmˈpæktɪv/
KK: /ɪmˈpæktɪv/
Relating to or having the effect of a strong influence or impact.
The impactive speech moved the audience to tears.
Impactive is formed from "im-" (meaning into or in) and "pact" (from Latin "pactum", meaning agreement or contract) with the suffix "-ive" (meaning having the nature of). The word describes something that has the nature of making an impact or having a strong effect.
Think of something that is 'into' ('im-') an 'agreement' or 'contract' ('pact') — this helps you remember that 'impactive' means having a strong effect.