Similar meaning, but slightly less intense:
* Impertinent: This word suggests rudeness and disrespect, but can be less aggressive than "insolent."
* Disrespectful: Focuses on the lack of regard shown.
* Rude: A general term for impolite behavior.
* Saucy: This word implies a playful or cheeky rudeness.
* Brazen: Suggests boldness and a lack of shame in being disrespectful.
More intense synonyms:
* Contemptuous: Expresses a feeling of superiority and disdain.
* Scornful: Similar to "contemptuous" but with a greater emphasis on disgust.
* Defiant: Indicates an open challenge to authority or rules.
* Scurrilous: Suggests low and vulgar language or behavior.
* Abusive: Implies verbal or physical attack.
More specific synonyms depending on the context:
* Insubordinate: Used specifically for refusing to obey orders or authority.
* Incendiary: Used for provocative speech or behavior that is likely to cause anger.
* Provocative: Used for behavior that is intended to incite a reaction.
The best substitute will depend on the specific context and the emotional tone you want to convey.