Lexical Etymology: Roots, Affixes

Take a look at the following words. Which one do you think does NOT belong?

predetermine              illogical               president            disappear


Prefixes are placed at the beginning of a root word to modify or change its meaning

All of the words above have prefixes added to the beginning of the root words except for president.

  • Predetermine (pre-) : to determine before
  • Illogical (il-) : not logical
  • Disappear (dis-) : no longer to be present

Even though it seems as though president has the prefix “pre-,” there is no such root word as “sident” in the English language!

Two of the words with prefixes are verbs (predetermine, disappear) and one of them is an adjective (illogical). When adding a prefix to an adjective, it usually changes the meaning of the root word into its opposite:

  • illogical = not logical (the “il-“ means “not”)

The meanings of nouns and verbs are often changed into their opposites by adding prefixes. There are a wide range of ways that prefixes can change meaning, however, for instance:

  • predetermine = determine beforehand (the “pre-“ means “before”)
  • ex-girlfriend = previous girlfriend (the “ex-“ means “previous”)
  • disappear = not appear, or not be seen (the “dis-“ means “not”)

As mentioned, there are words that look like they begin with a prefix but in fact do not.

For example:

  • prepare
  • illustrate
  • exercise
  • distance

These words are already in their root form and they cannot be broken down (pare, lustrate, ercise, and tance are not root words!).

Take a look at the following words. Which one do you think does NOT belong with the others?

affordable           comment            treatment           sadness


Suffixes are a group of letters placed at the end of a word to create a new word or to transform a word into a different part of speech.

All of the words above have suffixes added to the end of the root words except for comment.

  • affordable (-able) : able to afford
  • treatment (-ment): the act of getting treated
  • sadness (-ness) : the state of being sad

The “-ment” in comment is part of the root word form and cannot be separated from “com”.

Suffixes are different from prefixes in that they can not only change the meaning of a word, but they also change it into a different part of speech:

  • afford (verb) + -able (suffix) = affordable (adjective)
  • teach (verb) + -er (suffix) = teacher (noun)
  • establish (verb) + -ment (suffix) = establishment (noun)

Unlike words with prefixes, the word stress can sometimes change with words that have suffixes added to them. For example:

  • stupid (stress is on the 1st syllable) → stupidity (stress is on the 2nd syllable)
  • renovate (1st syllable) → renovation (3rd syllable)
  • congratulate (2nd syllable) → congratulations (4th syllable)

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