English Reference
noun

conversion

n.
US /kənˈvɝʒən/ UK /kənvˈɜːʃən/ con·ver·sion UK spelling conversions

  1. 01 B2 Upper Intermediate

    the act of changing something from one form or use to another.

    the process of changing or causing something to change from one form, function, or state to another.

    Simple

    The conversion of the old factory into luxury apartments took nearly two years.

    In context

    The rapid conversion of kinetic energy into heat during the braking process can cause the mechanical components to fail if not properly ventilated.

  2. 02 B2 Upper Intermediate

    a change in your religion or your core beliefs.

    the adoption of a new religion or belief system, often involving a formal process or public declaration.

    Simple

    His conversion to Buddhism happened after he spent a summer traveling through Asia.

    In context

    The historian examined the mass conversion of the local population following the arrival of the missionaries in the seventeenth century.

    proselytizationrebirth
  3. 03 B1 Intermediate

    changing a value from one system of measurement to another.

    the process of calculating the equivalent value of a sum or measurement in a different system.

    Simple

    The online tool makes the conversion from miles to kilometers very easy.

    In context

    Fluctuations in the exchange rate meant that the conversion of the company's overseas profits resulted in a significant loss on the balance sheet.

  4. 04 C1 Advanced Technical Computing

    when a person sees an online ad and then does what the advertiser wants, like buying a product.

    a marketing metric representing a user completing a desired action, such as a purchase or a newsletter sign-up.

    Simple

    The new website design led to a huge increase in sales conversions.

    In context

    The marketing team analyzed the conversion rate of the email campaign to determine which subject lines resonated most with the target demographic.

    Usage

    Often used in the compound 'conversion rate'.

  5. 05 C2 Proficiency FormalTechnical Law

    taking someone else's property and treating it as your own.

    the civil wrong of intentionally taking or using someone else's personal property without permission.

    Simple

    The company was sued for conversion after they refused to return the leased equipment.

    In context

    The plaintiff alleged conversion, claiming the defendant had sold the disputed assets despite knowing they were subject to a lien.

    misappropriationtheft
  6. 06 C1 Advanced AcademicTechnical Science

    creating a new word by using an existing word as a different part of speech.

    a word-formation process where a word changes its grammatical category without any change to its form.

    Simple

    The word 'email' started as a noun, but through conversion, we now use it as a verb.

    In context

    Functional conversion is a common feature of English, allowing nouns like 'Google' to transition seamlessly into verbs in everyday discourse.

    zero derivation
  7. 07 B2 Upper Intermediate Sport

    extra points scored by kicking the ball over the bar after a goal or try.

    a successful kick at a goal after a try in rugby or a touchdown in American football.

    Simple

    The kicker missed the conversion, so the team only got five points instead of seven.

    In context

    After scoring a dramatic try in the final minute, the captain stepped up to take the conversion that would win the match.

    extra point
  8. 08 C1 Advanced SlangInformal

    changing a toy or model figure to look like a different character.

    the modification of a miniature figure by swapping parts or using sculpting materials to create a unique model.

    Simple

    He showed off his latest conversion, a robot made from three different model kits.

    In context

    The hobbyist spent weeks on the conversion, carefully filing down the plastic joints to ensure the new limbs looked natural on the figure.

    modificationkitbash

Ministers have now decided this will apply to all pubs facing the threat of conversion into another use.

The Guardian· 16 Aug 2026

The updated National Planning Policy Framework (NPPF) will come into force on Monday and is expected to contain more protections for pubs at threat of closure for conversion to another use.

BBC News· 16 Aug 2026

From Middle English conversion, conversioun, borrowed from Anglo-Norman conversion, from Latin conversiō, from convertō.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Latin conversiō
Level C1 · Advanced
Frequency Common
Updated