That which is exhibited to the eye; the appearance which
anything manifests, especially any one among different and varying
appearances of the same object.

A particular appearance or state in a regularly recurring
cycle of changes with respect to quantity of illumination or form of
enlightened disk; as, the phases of the moon or planets. See Illust.
under Moon.

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.