1. A distinct stage of development: "The American occupation of Japan fell into three successive phases" (Edwin O. Reischauer).
2. A temporary manner, attitude, or pattern of behavior: just a passing phase.
3. An aspect; a part: every phase of the operation.
4. Astronomy One of the cyclically recurring apparent forms of the moon or a planet.
5. Physics
   1. A particular stage in a periodic process or phenomenon.
   2. The fraction of a complete cycle elapsed as measured from a specified reference point and often expressed as an angle.
   3. Any of the forms or states, solid, liquid, gas, or plasma, in which matter can exist, depending on temperature and pressure.
   4. A discrete homogeneous part of a material system that is mechanically separable from the rest, as is ice from water.
6. Chemistry
   1. Any of the forms or states, solid, liquid, gas, or plasma, in which matter can exist, depending on temperature and pressure.
   2. A discrete homogeneous part of a material system that is mechanically separable from the rest, as is ice from water.
7. Biology A characteristic form, appearance, or stage of development that occurs in a cycle or that distinguishes some individuals of a group: the white color phase of a weasel; the swarming phase of locusts.

1. To plan or carry out systematically by phases.
2. To set or regulate so as to be synchronized.

Synonyms: These nouns refer to a particular or possible way of viewing something, such as an object or a process: Phase refers to a stage or period of change or development: "A phase of my life was closing tonight, a new one opening tomorrow" (Charlotte Brontë).
Aspect is the way something appears at a specific vantage point: considered all aspects of the project.
A facet is one of numerous aspects: studying the many facets of the intricate problem.
Angle suggests a limitation of perspective, frequently with emphasis on the observer's own point of view: the reporter's angle on the story.
Side refers to something having two or more parts or aspects: "Much might be said on both sides" (Joseph Addison).