The phrase "hang by the neck until dead" refers to the act of executing someone by hanging them using a rope tied around their neck. This phrase is often used in legal contexts or historical accounts of capital punishment. However, there are also other phrases that can be used to describe this practice, such as "hanged by the neck", "strung up", "lynched", "executed by hanging", "sentenced to death by hanging", or "put to the gallows". These synonyms are less graphic and may be preferred in polite or sensitive company, while still conveying the serious nature of the punishment.