Chemistry. the process of cracking low-octane petroleum fractions in order to increase the octane number.

Nearby words

  1. reformatory,
  2. reformed,
  3. reformed church in america,
  4. reformed spelling,
  5. reformer,
  6. reformism,
  7. reformist,
  8. reformulate,
  9. refract,
  10. refractile

Origin of reforming

First recorded in 1920–25; reform + -ing1

Related formsan·ti·re·form·ing, adjective, nounun·re·form·ing, adjective



verb (used with or without object)

to form again.

Origin of re-form

1300–50; Middle English; orig. identical with reform

Related formsre-for·ma·tion, nounre-form·er, noun

Can be confusedre-form reform




the improvement or amendment of what is wrong, corrupt, unsatisfactory, etc.: social reform; spelling reform.
an instance of this.
the amendment of conduct, belief, etc.

verb (used with object)

to change to a better state, form, etc.; improve by alteration, substitution, abolition, etc.
to cause (a person) to abandon wrong or evil ways of life or conduct.
to put an end to (abuses, disorders, etc.).
Chemistry. to subject to the process of reforming, as in refining petroleum.

verb (used without object)

to abandon evil conduct or error: The drunkard promised to reform.


(initial capital letter) of, relating to, or characteristic of Reform Jews or Reform Judaism: a Reform rabbi.

Origin of reform

1300–50; (v.) Middle English reformen < Middle French reformer, Old French < Latin refōrmāre (see re-, form); (noun) partly derivative of the v., partly < French réforme

Related forms
Can be confusedre-form reform Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for reforming

British Dictionary definitions for reforming



(tr) to improve (an existing institution, law, practice, etc) by alteration or correction of abuses
to give up or cause to give up a reprehensible habit or immoral way of life
chem to change the molecular structure of (a hydrocarbon) to make it suitable for use as petrol by heat, pressure, and the action of catalysts


an improvement or change for the better, esp as a result of correction of legal or political abuses or malpractices
a principle, campaign, or measure aimed at achieving such change
improvement of morals or behaviour, esp by giving up some vice
Derived Formsreformable, adjectivereformative, adjectivereformer, noun

Word Origin for reform

C14: via Old French from Latin reformāre to form again



to form anew
Derived Formsre-formation, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for reforming
Online Etymology Dictionary, © 2010 Douglas Harper