from
The Collaborative International Dictionary of English v.0.48
Phase \Phase\ (f[=a]z), n.; pl. {Phases} (f[=a]z"[e^]z). [NL.
phasis, Gr. fa`sis, fr. fai`nein to make to appear: cf. F.
phase. See {Phenomenon}, {Phantom}, and {Emphasis}.]
1. That which is exhibited to the eye; the appearance which
anything manifests, especially any one among different and
varying appearances of the same object.
[1913 Webster]
2. Any appearance or aspect of an object of mental
apprehension or view; as, the problem has many phases.
[1913 Webster]
3. (Astron.) 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}.
[1913 Webster]
4. (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.
[1913 Webster]
5. (Phys. Chem.) A homogenous, physically distinct portion of
matter in a system not homogeneous; as, the three phases,
ice, water, and aqueous vapor; in a mixture of gasoline
and water, the gasoline will settle as the upper phase. A
phase may be either a single chemical substance or a
mixture, as of gases.
[Webster 1913 Suppl.]
6. (Zool.) In certain birds and mammals, one of two or more
color variations characteristic of the species, but
independent of the ordinary seasonal and sexual
differences, and often also of age. Some of the herons
which appear in white and colored phases, and certain
squirrels which are sometimes uniformly blackish instead
of the usual coloration, furnish examples. Color phases
occur also in other animals, notably in butterflies.
[Webster 1913 Suppl.]
7. (Physics) the relation at any instant of any cyclically
varying physical quantity, such as voltage in an A.C.
circuit, an electromagnetic wave, a sound wave, or a
rotating object, to its initial value as expressed as a
fractional part of the complete cycle. It is usually
expressed in angular measure, the complete cycle being
360[deg]. Such periodic variations are generally well
represented by sine curves; and phase relations are shown
by the relative positions of the crests and hollows of
such curves. Magnitudes which have the same phase are said
to be in phase.
Note: The concept of phase is also applied generally to any
periodically varying phenomenon, as the cycle of
daylight. One person who sleeps during the day and
another who sleeps at night may be said to be out of
phase with each other.
[PJC]
8. Specifically: (Elec.) The relation at any instant of a
periodically varying electric magnitude, as electro-motive
force, a current, etc., to its initial value as expressed
in factorial parts of the complete cycle. It is usually
expressed in angular measure, the cycle being four right
angles, or 360[deg].
[Webster 1913 Suppl.]