1. comparative form of deadly; more likely to cause death or serious harm
2. comparative form of deadly; more accurate or effective in causing damage

Examples

• The new strain of the virus proved deadlier than the original.
• Snakes are generally deadlier than spiders in this region.
• The archer became deadlier with each year of practice.
• Winter storms in the mountains are deadlier than those at sea level.
• Her second serve was deadlier than her first.
• The combination of drugs made the treatment deadlier than expected.