discourtesy

1. Lack of courtesy; rudeness.
2. A rude act or statement.

noun

The state or quality of being impudent or arrogantly self-confident: assumption, audaciousness, audacity, boldness, brashness, brazenness, cheek, cheekiness, chutzpah, disrespect, effrontery, face, familiarity, forwardness, gall¹, impertinence, impudence, impudency, incivility, insolence, nerve, nerviness, overconfidence, pertness, presumptuousness, pushiness, rudeness, sassiness, sauciness. Informal brass, crust, sauce, uppishness, uppityness. See attitude/good attitude/bad attitude/neutral attitude, courtesy/discourtesy.

The noun has 3 meanings:

Meaning #1: an expression of lack of respect
  Synonym: disrespect

Meaning #2: a manner that is rude and insulting
  Synonym: rudeness
  Antonym: courtesy (meaning #3)

Meaning #3: a lack of politeness; a failure to show regard for others; wounding the feelings or others
  Synonyms: offense, offence, offensive activity