# phase out

CEFR B2 · Phrasal verb

Source: https://englishreference.com/word/phase-out
Updated: 2026-10-22

## Definition

to stop using or doing something slowly, in stages, rather than all at once. You use this when a company or government replaces an old product or rule with a new one over time.

For teachers: to gradually withdraw something from use or existence through a series of planned stages. Transitive; frequently employed in the passive voice within administrative, industrial, or legislative contexts.

## Examples

- The company will phase out plastic bags by next year.
- After the new software was released, the IT department began to phase out the older version to ensure a smooth transition for all employees.
- Environmental regulations mandate that the automotive industry phase out internal combustion engines in favor of electric alternatives over the next two decades to meet carbon neutrality targets.

## Pitfalls

- Not "They decided to phase the old system." but "They decided to phase out the old system." — the particle 'out' is essential to convey the meaning of gradual removal; 'phase' alone usually refers to a stage of development.

## Usage notes

- often used in the passive voice when the focus is on the thing being removed.
- Teaching tip: contrast with 'discontinue' to highlight the deliberate, step-by-step nature of the process; it is the direct antonym of 'phase in'.

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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.