Harmless

Harmless is an adjective describing something that is not capable of causing harm, injury, or damage. It can apply to people, actions, substances, animals, or situations. The term implies a lack of potential to cause harm under typical circumstances, though context matters and effects may vary with dose, exposure, or individual sensitivity.

In medicine and biology, a harmless agent is nonpathogenic or nontoxic; for example, many benign bacteria are harmless to humans, and a harmless substance produces no adverse effects at normal exposure. In law, the phrase harmless error refers to a procedural mistake that did not affect the outcome of a trial and thus does not warrant reversal.

Harmless is related to benign and innocuous. Benign is common in clinical contexts to describe noncancerous tumors or favorable conditions, innocuous emphasizes lacking offensiveness or danger in social terms, while harmless stresses safety from injury or damage. But these terms are not always interchangeable.

Origin: from harm + less, dating from Old English and Middle English; it has long been used to denote absence of harm rather than moral neutrality.

Usage notes: People may describe jokes or pranks as harmless when intended to be lighthearted; nevertheless, harm can occur in unforeseen ways, so caution is advised.