“She can be pretty cheeky even with her teachers.”

Coarse (adjective) Rude and offensive.

“A coarse language.”

Cocky (adjective) used in informally to describes a young person who is confident, but in a rude and unpleasant way.

Crass (adjective) thoughtless and vulgar, lacking refinement or delicacy.

“A crass remark.”

Crude (adjective) rude and offensive.

“A crude joke.”

Foul-mouthed (adjective) if someone is foul-mouthed, they swear a lot and use offensive language.

Gall (noun) audacity, impudent boldness and the quality of being unable to understand that your behaviour or what you say is not acceptable to other people.

“Despite getting such poor marks in the test, he had to gall to ask his parents for a gift!”

Impertinent (adjective) rude and not respectful, especially towards someone older or in a higher position than you.
Insolent (adjective) rude and not showing respect.

“An insolent child.”

Irreverent (adjective) not showing the expected respect for official, important or holy things.

Neanderthal (adjective) very old-fashioned and not willing to change.

Obnoxious (adjective) very unpleasant or rude.

“I don't want to be friends with him because he is too obnoxious.”

Sass (verb) to talk to someone in a rude way.

Saucy (adjective) rude and showing no respect.

Snotty (adjective) an offensive term meaning behaving in an arrogant and condescending manner; describing actions that are regarded as mean or rude.

“She has become rather snooty since she was elected the head girl in the class.”

Surly (adjective) often in a bad mood, unfriendly and not polite.

“He gave me a surly look.”

— Ahzam Ahmed