Which word would best describe an intentional act of harm?

The term "malicious" is defined as characterized by the intention to commit harm or to cause injury. When someone performs an act with malice, it implies a deliberate desire to cause pain or distress to others. In the context of the question, an intentional act of harm clearly aligns with this definition, as it highlights the purposeful nature of the action taken against another individual or entity.

In contrast, the other terms suggest meanings that do not align with the idea of intentional harm. "Accidental" refers to something that happens unintentionally, lacking any aim to inflict damage. "Innocuous" describes something that is harmless, indicating no potential to cause injury at all. "Unintentional" also denotes actions taken without intent or forethought, reflecting a lack of purpose or desire to harm. Hence, "malicious" best captures the essence of an intentional act of harm, making it the correct choice.