<p><strong>Noun</strong></p><ul><li>Any of the major appearances or aspects in which a thing of varying modes or conditions manifests itself to the eye or mind.</li><li>A stage in a process of change or development: Each phase of life brings its own joys.</li><li>A side, aspect, or point of view: This is only one phase of the question.</li><li>A state of synchronous operation: to put two mechanisms in phase.</li><li>Astronomy: the particular appearance presented by the moon or a planet at a given time.</li><li>One of the recurring appearances or states of the moon or a planet in respect to the form, or the absence, of its illuminated disk: the phases of the moon.</li><li>Zoology: color phase.</li><li>Chemistry: a mechanically separate, homogeneous part of a heterogeneous system: the solid, liquid, and gaseous phases of a system.</li><li>Physics: a particular stage or point of advancement in a cycle; the fractional part of the period through which the time has advanced, measured from some arbitrary origin often expressed as an angle (phase angle), the entire period being taken as 360°.</li></ul><p><strong>Verb</strong></p><ul><li>(Used with object) to schedule or order in gradual stages, so as to be available when or as needed.</li><li>Physics: to adjust the phase of (an electrical or mechanical device), especially to synchronize it with that of one or more other devices: a properly phased, synchronous pulse generator that augments the action of the human heart.</li></ul><p><strong>Verb Phrase</strong></p><ul><li>To put or come into use gradually; incorporate by degrees: to phase in new machinery.</li><li>To reduce by gradual stages.</li><li>To bring or come to an end gradually; ease out of service: to phase out obsolescent machinery.</li></ul>