Spelling: Double consonants

If a root word ends in a consonant, adding a suffix will sometimes require that you double the base word’s final consonant. How do you know when to double the consonant?

Consider the following examples, where doubled consonants are underlined.

  • shipment
  • shipped
  • muddy
  • fitful
  • fittest
  • waiting
  • greenest

Now take a look at some larger words, whose base forms have more than one syllable.

  • visitor
  • occurring
  • balloted
  • committed

Below are the rules for doubling consonants when adding a suffix.

Rules

  1. Only double the final consonant of the root word if:
    1. the base form ends in the sequence consonant-vowel-consonant (CVC) and
    2. the suffix begins with a vowel and
    3. the stress is placed on the final (or only) syllable.
  2. Otherwise don’t double the consonant.

British English Note: Treat a final r as a consonant, even if you don’t pronounce it.

Let us consider some examples to see if these rules work.

Consider suffixes starting with a vowel (e.g. -ed, -ing, -er, -est, and in this case -y).

  • ship
  • The last three letters of ship are consonant-vowel-consonant: double the final p.
    • ship + −edshipped
    • ship + −ingshipping
  • green
  • Green ends in vowel-vowel-consonant: don’t double the final n.
    • green + −ergreener
    • green + −estgreenest

    Here are some more examples. Do they match the rules we just stated?

    Spot the root word in each case.

    • whirring
    • occurring
    • tighten
    • lifted
    • visitor
    • balloted
    • committed
    • accountable
    • famished
    • friendship

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