1. the quality or state of being harmful; the capacity to cause damage, injury, or negative effects

Examples

• The harmfulness of smoking is well documented by medical research.
• Scientists debate the harmfulness of artificial sweeteners in our diet.
• The harmfulness of plastic pollution to marine life cannot be ignored.
• Parents worry about the harmfulness of excessive screen time for children.
• The report highlighted the harmfulness of the chemical compound.
• Despite its harmfulness, the pesticide was widely used in agriculture.