# phase

/ˈfeɪz/ (US) · /fˈeɪz/ (UK)

Source: https://englishreference.com/word/phase
Updated: 2026-06-19

## Senses

### 1. a stage in a process

noun · CEFR B2 · General-service

one part of a process or a stage in someone's development.

For teachers: a distinguishable stage in a sequence of events or a period of development.

- Most teenagers go through a phase where they want to be alone in their rooms.
- The first phase of the construction project involves clearing the site and laying the foundation before the winter weather sets in.

### 2. astronomy

noun · CEFR B2 · Technical

the changing shape of the bright part of the moon or a planet.

For teachers: the particular appearance of a celestial body's illuminated disk in a recurring cycle.

- The moon is in its crescent phase tonight.
- Astronomers track the lunar phases to predict tidal patterns and optimal conditions for deep-space observation.

### 3. chemistry/physics

noun · CEFR C1 · Academic · Technical

a state of matter, such as being a solid, liquid, or gas.

For teachers: a physically distinctive form of matter, such as a solid, liquid, gas, or plasma.

- When water boils, it changes from a liquid phase to a gas phase.
- The experiment demonstrated how the substance remains stable in its solid phase even under extreme atmospheric pressure.

### 4. physics/waves

noun · CEFR C1 · Academic · Technical

a specific point in a repeating movement, like a wave or vibration.

For teachers: the position of a point in time on a waveform cycle.

- If two sound waves are out of phase, they can cancel each other out.
- The engineers adjusted the signal timing to ensure the two oscillators remained in phase, preventing destructive interference.

### 5. to introduce or remove gradually

verb · CEFR B2

to start or stop something in gradual steps rather than all at once.

For teachers: to introduce or withdraw something in planned stages; typically used with 'in' or 'out'.

- The company will phase out the old software over the next six months.
- The government plans to phase in the new tax regulations over a three-year period to minimize the economic impact on small businesses.

Usage: Usually functions as a phrasal verb: 'phase in' or 'phase out'.

## Examples

- The construction project is now in its final phase.
- Most toddlers go through a phase where they refuse to eat any green vegetables.
- The research team is currently transitioning from the data collection phase to the analytical stage of the study, which requires a different set of technical skills.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.