IPA: /əˈstaʊndɪŋli/
KK: /əˈstaʊndɪŋli/
In a way that causes great surprise or amazement.
The magician performed astoundingly, leaving the audience in awe.
Astoundingly → It is formed from "astound" (from Old French *estoundre*, meaning to stun or shock) and the suffix "-ingly" (meaning in a manner of). The word "astoundingly" means in a manner that stuns or shocks.
Think of being so shocked or stunned by something that it leaves you in awe — that's what astoundingly means.