1. extremely mean, cruel, or cowardly

Examples

• The villain hatched a dastardly plan to steal the treasure.
• It was a dastardly act to abandon the injured hiker.
• The dastardly scheme involved cheating elderly people out of their savings.
• He was known for his dastardly behavior toward his employees.
• The movie featured a dastardly character who terrorized the town.
• Such dastardly conduct has no place in civilized society.