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#35 Forms of "con-"


Quick Summary

Prefixes often undergo spelling changes depending upon the stem, or main part of the word, to which they are affixed. The prefix con-, for example, can exist in the following forms: co-, col-, com-, and cor-. Examples of words containing such forms include cooperate, collaborate, companion, and correct.

From Membean

The word ingredient Memlet, shown below, is one of many ways that a word is taught in Membean.
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Ingredient Memlet: compulsion

com- thoroughly
puls pushed
-ion act, state, or result of doing something

One who suffers from a compulsion is “thoroughly pushed” into doing something.

Ingredient Memlet: corroborate

cor- thoroughly
robor oak, strength
-ate make something have a certain quality

To corroborate existing evidence is to make it “thoroughly strong” or “strong as an oak,” thereby making that evidence even more compelling.

Different Spellings of the Prefix “Con-”

Today we will focus on the different spelling changes of the English prefix con-, which means “with” or “thoroughly.” Not only do prefixes usually have several different meanings, but they also change their form to accommodate the stem to which they are attached. These spelling changes of prefixes primarily occur to make a word easier to say. The prefix con-, for example, can exist in the following forms: co-, col-, com-, and cor-.

Take, for instance, the word “cooperate.” Cooperate consists of three morphemes: the prefix con-, the stem or root “oper,” and the suffix “-ate.” Together they etymologically mean “to make work together.” Note that con- changed its spelling to co-: it has undergone prefix assimilation so that the word sounds better. Can you hear why “cooperate” is preferable to “conoperate?”

Recalling that the prefix con- can mean “with” or “thoroughly,” let’s go through examples of the four spelling variants in which con- exists in English:


  • Co-cooperate: “to work with” and coexisting: “existing with.” Note how the “co-” spelling is preferable to conoperate or conexisting!
  • Col-collaborate: “work with” and collapse: “thoroughly slip or fall.”
  • Com-combat: “a fighting with;” companion: “one with whom one eats bread;” and complete: “to thoroughly fill.”
  • Cor-correct: “make thoroughly right;” corrode: “thoroughly eat or gnaw away;” and correlate: “to relate with.”

A good way to remember that con- can also exist as co-, col-, com-, and cor- is the following mnemonic: Cold Cola Comforts Your Core.


The prefix con- not only has two primary meanings: “with” and “thoroughly,” but also has four ways it can be spelled: co-, col-, com-, and cor-. This completes our comprehensive study of the prefix con-, “with” which you can now be “thoroughly” comfortable!

  1. cooperate: to work ‘with’ another
  2. coexisting: existing ‘with’
  3. collaborate: to work ‘with’ another
  4. collapse: to ‘thoroughly’ fall
  5. combat: fight ‘with’
  6. companion: one ‘with’ whom one eats bread
  7. complete: ‘thoroughly’ fill
  8. correct: make ‘thoroughly’ right
  9. corrode: ‘thoroughly’ eat away
  10. correlate: relate ‘with’