IPA: /ˈbʌmpʃəsli/
KK: /ˈbʌmpʃəsli/
In a way that is overly confident or self-assertive, often in a rude or annoying manner.
He spoke bumptiously at the meeting, making everyone uncomfortable with his arrogance.
Bumptiously → It is formed from "bump" (originating from Middle English *bumpen*, meaning to thump or strike) and the suffix "-iously" (meaning in a manner characterized by). The word "bumptiously" describes behaving in a self-assertive or arrogant manner, as if striking or thumping one's presence.
Think of someone behaving in a way that 'thumps' their presence ('bump') and doing so 'in a manner' ('-iously') that is assertive or arrogant.