IPA: /dɪsˈkɜːrtəsli/
KK: /dɪsˈkɜrtəsli/
In a way that shows a lack of respect or politeness towards others.
He spoke discourteously to his colleagues during the meeting.
Discourteously → It is formed from "dis-" (meaning apart or away) and "courteous" (from Old French *courtois*, meaning polite or refined). The word describes behavior that is away from politeness or refinement, hence lacking courtesy.
Think of being 'away from' ('dis-') being 'polite' ('courteous') — that's why discourteously means acting without politeness.