phase

American  

[feyz] / feɪz /

noun

phases plural

1. any of the major appearances or aspects in which a thing of varying modes or conditions manifests itself to the eye or mind.

   Synonyms:

   side, facet, shape, form

2. a stage in a process of change or development.

   Each phase of life brings its own joys.

3. a side, aspect, or point of view.

   This is only one phase of the question.

4. a state of synchronous operation.

   to put two mechanisms in phase.

5. Astronomy.

   1. the particular appearance presented by the moon or a planet at a given time.

   2. 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.

6. Zoology. color phase.

7. Chemistry. a mechanically separate, homogeneous part of a heterogeneous system.

   the solid, liquid, and gaseous phases of a system.

8. 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°.

---

verb (used with object)

phases, present (3rd person singular) phased, past participle, past phasing present participle

1. to schedule or order in gradual stages, so as to be available when or as needed.

2. 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.

verb phrase

1. phase in to put or come into use gradually; incorporate by degrees.

   to phase in new machinery.

2. phase down to reduce by gradual stages.

3. phase out to bring or come to an end gradually; ease out of service.

   to phase out obsolescent machinery.

phase British  

/ feɪz /

noun

1. any distinct or characteristic period or stage in a sequence of events or chain of development

   there were two phases to the resolution

   his immaturity was a passing phase

2. astronomy one of the recurring shapes of the portion of the moon or an inferior planet illuminated by the sun

   the new moon, first quarter, full moon, and last quarter are the four principal phases of the moon

3. physics

   1. the fraction of a cycle of a periodic quantity that has been completed at a specific reference time, expressed as an angle

   2. ( as modifier )

      a phase shift

4. physics a particular stage in a periodic process or phenomenon

5. (of two waveforms) reaching corresponding phases at the same time

6. (of two waveforms) not in phase

7. chem a distinct state of matter characterized by homogeneous composition and properties and the possession of a clearly defined boundary

8. zoology a variation in the normal form of an animal, esp a colour variation, brought about by seasonal or geographical change

9. biology (usually in combination) a stage in mitosis or meiosis

   prophase

   metaphase

10. electrical engineering one of the circuits in a system in which there are two or more alternating voltages displaced by equal amounts in phase (sense 5) See also polyphase

11. (in systemic grammar) the type of correspondence that exists between the predicators in a clause that has two or more predicators; for example connection by to, as in I managed to do it, or -ing, as in we heard him singing

---

verb

1. (often passive) to execute, arrange, or introduce gradually or in stages

   a phased withdrawal

2. (sometimes foll by with) to cause (a part, process, etc) to function or coincide with (another part, process, etc)

   he tried to phase the intake and output of the machine

   he phased the intake with the output

3. to arrange (processes, goods, etc) to be supplied or executed when required

phase Scientific  

/ fāz /

1. Any of the forms, recurring in cycles, in which the Moon or a planet appears in the sky.

2. One of a set of possible homogenous, discrete states of a physical system. States of matter such as solid and liquid are examples of phases, as are different crystal lattice structures in metals such as iron.

3. See also phase transition state of matter

4. A measure of how far some cyclic behavior, such as wave motion, has proceeded through its cycle, measured in degrees or radians. At the beginning of the phase, its value is zero; at one quarter of its cycle, its phase is 90 degrees (π/2 radians); halfway through the cycle its value is 180 degrees (π radians), and so on.

5. ◆ The phase angle between two waves is a measure of their difference in phase. Two waves of the same frequency that are perfectly in phase have phase angle zero; if one wave is ahead of the other by a quarter cycle, its phase angle 90 degrees (π/2 radians); waves that are perfectly out of phase have phase angle 180 degrees (π radians), and so on.

6. See more at wave

---

Other Word Forms

Derived Forms

• subphase
  noun
• rephase
  verb (used with object)
• phaseal
  adjective
• phaseless
  adjective
• phasic
  adjective
• unphased
  adjective

Inflected Forms

Nouns

• phases
  plural

Participles

• phasing
  present
• phased
  past

Conjugated Forms

Present

• phase
  simple
• phases
  simple
• have phased
  perfect
• has phased
  perfect
• am phasing
  progressive
• are phasing
  progressive
• is phasing
  progressive
• have been phasing
  perfect progressive
• has been phasing
  perfect progressive

Past

• phased
  simple
• had phased
  perfect
• was phasing
  progressive
• were phasing
  progressive
• had been phasing
  perfect progressive

Future

• will phase
  simple
• will have phased
  perfect
• will be phasing
  progressive
• will have been phasing
  perfect progressive

Etymology

Origin of phase

First recorded in 1805–15; (noun) back formation from phases, plural of phasis

Explanation

A phase is a particular period of time, like someone whose "teenage rebellion" phase lasts well into her thirties. The word phase can mean a stage in a person’s development or a step in a process, such as “the next phase in the Interstate 57 project.” Phase can also be a verb, usually followed by in or out, to mean slowly introducing or getting rid of something. For example, your school might phase in a new rule or phase out an old one, as new students arrive.

Example Sentences

See Examples For:

phase phases phased phasing

The next phase of the research will move from the laboratory to the open ocean.

From Science Daily ● Jul. 12, 2026

This disagreement is rooted in the inconclusive nature of the full-scale phase of the conflict that lasted for 40 days between February and April.

From The Wall Street Journal ● Jul. 11, 2026

When will this phase of “low-hire and low-fire” end?

From MarketWatch ● Jul. 11, 2026

"We try to work together with the polluters, and slowly phase them out," says Oscar van Veen, director of innovation at the Port of Rotterdam, speaking on a small boat in the harbour.

From BBC ● Jul. 9, 2026

And with the sugar-phosphate backbone placed on the outside, and the general parameters of the measurements ascertained, the model builders could begin the most exacting phase of model building.

From "The Gene" by Siddhartha Mukherjee

Or, take the example of Japan, another place with a deep civilizational history that’s gone through many phases when it comes to types of government.

From Slate ● Jul. 4, 2026

DGC's education committee is being advised to start the statutory process, involving a number of phases, which would lead to it being closed permanently.

From BBC ● Jun. 30, 2026

It’s part of a wider plan to connect the E Line to the city of Whittier, though officials say the work will be built in two phases due to funding constraints.

From Los Angeles Times ● Jun. 19, 2026

"Perhaps the greatest emotion is feeling a bit as if you were up on the scaffolding with Giotto... retracing the creative phases in the making of a masterpiece like this," she said.

From Barron's ● Jun. 12, 2026

We have seen already that the two-spheres theory could not survive the discovery of America; now we find that traditional Ptolemaic astronomy could not survive the discovery of the phases of Venus.

From "The Invention of Science" by David Wootton

Even with the bad luck of the market moving against them, annuitants live longer on average than retirees who take phased withdrawals, Previtero said.

From MarketWatch ● Jul. 2, 2026

The LAF will "gradually assume full and effective security responsibility in pilot zones, which will serve as the mechanism for phased and verified redeployments of the IDF and the deployments of the LAF."

From Barron's ● Jun. 27, 2026

Most households remain under pressure from a mix of slowing income growth and rising living costs, which will weigh on private consumption once government relief measures are phased out, the central bank added.

From The Wall Street Journal ● Jun. 24, 2026

"Hospitality is stressed and I understand that," he said, pointing to the government's recent announcement that business rate rises for pubs would be phased in more gradually than originally planned.

From BBC ● Jun. 10, 2026

But first they were unmade, their edges fading like the evanescent white bird, Wraith, as it phased through the skin of the sky.

From "Strange the Dreamer" by Laini Taylor

Lloyds Banking Group, which has owned Halifax since 2009, confirmed the move after reports in May said it was considering phasing out Halifax as a standalone brand.

From BBC ● Jul. 1, 2026

Starting today, the federal government will put new limits on certain types of borrowing, begin phasing out longstanding repayment programs and launch a new one.

From MarketWatch ● Jul. 1, 2026

“At the least, the phasing out of test-based accountability made the pre-pandemic losses harder to recognize,” says a recent Education Scorecard report from Harvard and Stanford researchers.

From The Wall Street Journal ● Jun. 12, 2026

United Parcel Service said it is in the home stretch of a years-long restructuring that includes phasing out roughly half its Amazon business, as well as cutting tens of thousands of delivery-driver and warehouse-worker roles.

From The Wall Street Journal ● Apr. 30, 2026

He seemed in a state of constant transition, phasing in and out of dimensions, unsure whether to be my father’s son or his wife’s husband.

From "Educated" by Tara Westover

Related Words

• aspect
• chapter
• development
• point
• stage
• state
• step
• time