When it comes to describing someone who is angry or frustrated, there are plenty of synonyms for the phrase "is mad" that can be used to convey a similar meaning. Alternatives to this include phrases like "is furious," "is incensed," "is outraged," "is livid," "is seething," "is boiling," "is vexed," and "is irked." Each of these expressions describes someone who is feeling an intense emotion and is struggling to control their reaction to it. By using different synonyms for "is mad," a writer or speaker can add nuance and variety to their descriptions of emotions and create a more vivid picture for their audience.