discourteous
definition
showing a lack of courtesy or respect
example
It was discourteous of him to interrupt her while she was speaking.
synonyms
rudeimpoliteill-mannered
word origin — The word 'discourteous' comes from the prefix 'dis-' meaning 'not' and 'courteous', which originates from the Old French 'cortois', meaning 'courtly' or 'polite'.