"Foul on" is a term that's often used in sports, especially in games like basketball, soccer, and football. It refers to an illegal or unfair move made by a player that results in a penalty or free kick for the opposing team. There are several synonyms for the term "foul on" that can be used to make the language more varied and interesting. These include words like "violation," "infraction," "irregularity," "transgression," and "infringement." By using these synonyms, you can describe the action in a more precise and impactful way, adding depth and dimension to your writing.