Which term describes something that is harmless?

The term that specifically describes something that is harmless is "innocuous." This word is often used to refer to substances, statements, or actions that do not pose any threat or danger, making it a fitting choice for describing something that is devoid of harmful effects. It conveys a clear sense of safety and non-offensiveness.

While "benign" also means harmless, particularly in a medical context (like a benign tumor), "innocuous" generally applies to a broader range of situations, including everyday language and interactions. "Negligible" indicates something so small or unimportant that it can be disregarded, but it doesn’t necessarily convey harmlessness. Similarly, "trivial" refers to something of little importance or value, which again does not inherently relate to the idea of being harmless. Therefore, "innocuous" is the most precise term for describing something that is entirely benign or harmless in nature.