The term "brass-necked" refers to someone who is looked at as being impudent, audacious, and shameless. A person with this trait might behave in a way that can be considered as inappropriate or even offensive to others. There are several synonyms that can be used in place of "brass-necked," including brazen, bold, cheeky, impertinent, presumptuous, and insolent. All these words reflect the behavior of someone who displays an extreme level of self-confidence and often disregards the feelings or opinions of others. These synonyms can be used interchangeably, depending on the context of the sentence and the tone of the conversation.