Which term best describes behavior that shows a complete lack of respect?

The term that best describes behavior characterized by a complete lack of respect is "impudence." Impudence refers to a boldness or audacity that is often disrespectful and shows a disregard for authority or social norms. When someone exhibits impudence, they are acting in a way that is openly disrespectful, often challenging others, especially in situations where humility or respect is expected.

In contrast, the other terms present a sense of respect or reverence. "Politeness" implies good manners and consideration for others, which is the opposite of disrespectful behavior. "Veneration" refers to a profound respect or reverence, often reserved for individuals or things deemed sacred. "Deference" involves yielding to the judgment or opinions of others as a sign of respect. Therefore, these terms do not align with the notion of complete lack of respect that impudence embodies.