phase (fāz)

1. A characteristic form, appearance, or stage of development that occurs in a cycle or that distinguishes some individuals of a group.
2. A discrete homogeneous part of a material system that is mechanically separable from the rest, as is ice from water.
3. Any of the forms or states, solid, liquid, gas, or plasma, in which matter can exist, depending on temperature and pressure.
4. A particular stage in a periodic process or phenomenon such as a wave form or time pattern.