1. to bring under the control or authority of a federal government
2. to unite in or under a federal system

Examples

• The government decided to federalize the National Guard during the crisis.
• Congress voted to federalize airport security after the attacks.
• The plan would federalize education standards across all states.
• They want to federalize the healthcare system.
• The president moved to federalize disaster response efforts.
• Local authorities resisted attempts to federalize their police force.
• The new law will federalize environmental regulations.