1. to make stronger or more secure, especially by adding defensive structures
2. to add nutrients or other beneficial substances to food or drink
3. to give physical, mental, or moral strength to someone

Examples

• The army fortifies the border with concrete barriers.
• This cereal fortifies your diet with essential vitamins.
• Regular exercise fortifies the immune system.
• The castle fortifies the hilltop against enemy attacks.
• Milk fortifies children’s bones with calcium.
• Prayer fortifies her spirit during difficult times.
• The company fortifies its network security annually.