# Phases

/ˈfeɪzəz/ (US) · /fˈeɪzɪz/ (UK)

Source: https://englishreference.com/word/phases
Updated: 2026-08-15

## Senses

### 1. stages of a process

noun · CEFR B1

the different parts or stages of a project, process, or development.

For teachers: distinct stages or periods in a series of events or a process of change.

- The construction project will be completed in three separate phases over two years.
- The clinical trial is currently entering its final phases, with researchers monitoring long-term efficacy across a broader demographic.

### 2. astronomy

noun · CEFR B2

the different shapes the moon or a planet appears to have as it moves.

For teachers: the varying appearances of the illuminated portion of a planet or satellite as seen from Earth.

- We studied the phases of the moon in our science class last week.
- Ancient calendars were often based on the lunar phases, tracking the transition from new moon to full moon with high precision.

### 3. to introduce gradually

verb · CEFR B2

to start or finish something in stages rather than all at once.

For teachers: to carry out a plan or introduce a change in gradual steps; often used with 'in' or 'out'.

- The company phases in the new software slowly to avoid technical problems.
- The government phases out the old currency over six months to ensure the economy remains stable during the transition.

Usage: Often used in the phrasal verbs 'phase in' or 'phase out'.

## Examples

- The project has three main phases.
- The construction of the new library will be completed in several phases over the next two years.
- Astronomers track the lunar phases to predict tidal patterns, while biologists observe the distinct growth phases of organisms to understand their life cycles.

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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.