The phrase "speak ill" is often used to describe when someone is saying negative or critical things about another person. There are several synonyms that can be used interchangeably with this phrase, depending on the context and intended meaning. Some of the most common synonyms for "speak ill" include slander, malign, defame, disparage, belittle, insult, criticize, and denigrate. Each of these words carries a slightly different connotation, but ultimately they all refer to speaking negatively about someone else. It is important to be mindful of the impact that our words can have and to strive to speak kindly and respectfully towards others.