1. a gradual reduction or elimination of something over time

Examples

• The company announced a phaseout of its older product line.
• The phaseout of coal-powered plants will take several years.
• Environmental groups support the phaseout of single-use plastics.
• The military base closure was part of a larger phaseout plan.
• The phaseout of the old software system begins next month.
• Government subsidies will undergo a gradual phaseout over five years.