1. the process of making or becoming tough, strong, or resilient

1. present participle of toughen; making or becoming tough, strong, or resilient

Examples

• The toughening of the new regulations made compliance more difficult.
• Years of hard work led to the toughening of his character.
• The coach is toughening the team’s training regimen.
• Cold weather is toughening the plants for winter.
• The toughening process makes the glass more resistant to breaking.
• She noticed the toughening of her muscles after months of exercise.
• The company is toughening its hiring standards.