In a way that proves something beyond doubt or settles a matter finally.
From 'conclusive' (adjective), which comes from Latin 'conclusivus,' from 'concludere' meaning 'to close' or 'to shut.' The -ly suffix converts it to an adverb describing how an action happens.
The root 'concludere' literally means 'to close' or 'to shut'—so when you conclusively prove something, you're literally closing the door on doubt, which is why the word works perfectly for ending arguments!
Complete word intelligence in one call. Free tier — 50 lookups/day.