What adjective describes something that is gentle or mild in character and considered harmless?

The term that describes something that is gentle or mild in character and considered harmless is "benign." This adjective is often used in various contexts, such as medicine, where a benign tumor is one that is not cancerous and does not pose a serious threat to health. In general usage, describing a person or behavior as benign indicates that they are kind, non-threatening, and likely to have a positive influence. This quality of gentleness or harmlessness is at the core of what "benign" conveys, underscoring a sense of safety and comfort.

The other terms do not carry the same meaning of gentleness or harmlessness. "Brittle" suggests fragility or the tendency to break easily, which is contrary to the idea of being benign. "Candid" means being frank or honest, often in a way that may not regard gentleness, while "brash" describes someone who is bold in a rude or overbearing way, clear opposites to a gentle or mild disposition.