the.com/discourtesy
Manners caught playing hooky, leaving rudeness to babysit the conversation.
means A lack of politeness or consideration; behavior that ignores the basic respect others are owed.
from From Old French corteis, the courtly manner expected at court, with the prefix dis- bluntly canceling all that royal polish.
Class rootsCourtesy literally meant fit-for-court behavior.
Softer than rudeImplies neglect of manners, not active cruelty.
Legal cousinCourts once treated discourtesy as a punishable contempt.