1. a distinct stage or period in a process of change or development
2. each of the aspects of the moon or a planet, according to the amount of its illumination
Usage: astronomy
3. a distinct period or stage in a series of events or a process of change

1. to carry out something in gradual stages

Examples

• The project is entering its final phase.
• Teenagers often go through a rebellious phase.
• The moon is in its full phase tonight.
• We need to phase in the new system over six months.
• The construction will be completed in three phases.
• She’s going through a difficult phase right now.
• The company will phase out the old product line.