insolent
in-so-lent
adjective
Showing a rude and disrespectful lack of regard for others.
"The insolent child talked back to his teacher."
Thesaurus
Synonyms: unashamed, brazen-faced, bald-faced, brassy, audacious, bodacious, brazen, barefaced, flip, impudent, disrespectful, snotty-nosed