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°.

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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

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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

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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

Earlier this week, AI lab Thinking Machines announced its latest Inkling model, which used outputs generated by Kimi K2.5 during the fine-tuning phase.

From MarketWatch ● Jul. 17, 2026

"We're still in a hypergrowth phase," Lauer said.

From Barron's ● Jul. 17, 2026

It describes how energy is released from the chemical reactions of molecules in the gas phase.

From Los Angeles Times ● Jul. 17, 2026

But that only lasted a few months before he decided to revive Thotsakan – the band's "phase two" – with a new slate of musicians.

From BBC ● Jul. 16, 2026

“I thought the astronaut phase was last summer. What happened to your international spy ring?”

From "The Season of Styx Malone" by Kekla Magoon

You could say that frozen-yogurt trends come in crazes, not phases.

From The Wall Street Journal ● Jul. 19, 2026

Construction will be completed in phases over about a year.

From Los Angeles Times ● Jul. 17, 2026

Researchers describe three phases: the “go-go” years when you’re active and traveling, the “slow-go” years roughly from ages 70 to 84, and the “no-go” years shaped by health and end-of-life care.

From MarketWatch ● Jul. 16, 2026

"But the best team won. All the phases were controlled by Spain - we are used to what Spain are doing but they're doing it so well."

From BBC ● Jul. 15, 2026

All of this occurred during the hectic early phases of the TB project in Peru.

From "Mountains Beyond Mountains" by Tracy Kidder and Michael French

This could mean free allowances being phased out more slowly and extended beyond 2034, provided companies commit to long term decarbonisation.

From Barron's ● Jul. 17, 2026

About 20% of borrowers moved into the two older repayment plans that will be phased out by 2028.

From The Wall Street Journal ● Jul. 14, 2026

A retiree who purchases a lifetime annuity can be expected to live longer than the one who takes phased withdrawals from a retirement portfolio.

From MarketWatch ● Jul. 2, 2026

While the practice has been phased out, there are still believed to be about 200 bears living in cages at the former farms.

From BBC ● Jun. 29, 2026

It made my lungs feel heavy, my heart grow light, until the juxtaposition of the two phased into sleep.

From "The Marrow Thieves" by Cherie Dimaline

In its report, published on Wednesday, external, the committee recommended phasing in a retirement age of 80 and requiring members to attend at least 20% of sitting days.

From BBC ● Jul. 15, 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

Alison Fure, 68, is petitioning Kingston Council to begin phasing out plastic decorative items, including ornaments, flowers, and windmills, on graves.

From BBC ● Jun. 7, 2026

The period between the late eighteenth and the mid-nineteenth centuries, wrote Michel Foucault, saw “the disappearance of torture as a public spectacle” and the gradual phasing out of corporal punishments.

From "Newjack: Guarding Sing Sing" by Ted Conover

Related Words

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