A distinguishable part of a sequence or cycle occurring over time.
That which is exhibited to the eye; the appearance which anything manifests, especially any one among different and varying appearances of the same object.
Any appearance or aspect of an object of mental apprehension or view.
The problem has many phases.
(astronomy) A particular appearance or state in a regularly recurring cycle of changes with respect to quantity of illumination or form, or the absence, of its enlightened disk; as, the phases of the moon or planets. Illustrated in Wikipedia's article Lunar phase.
(physics) Any one point or portion in a recurring series of changes, as in the changes of motion of one of the particles constituting a wave or vibration; one portion of a series of such changes, in distinction from a contrasted portion, as the portion on one side of a position of equilibrium, in contrast with that on the opposite side.