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Week 4: General Rules For Adding Suffixes

Some General Rules for Adding Suffixes


Those of you who have read my last blog, may have noticed a certain pattern when adding the suffixes. Here are some very general rules that will help you correctly spell many words; however,remember that there are exceptions to these rules and as a speller you should always be on the lookout for them.


Rule 1. If a root word ends with a consonant (not a y- see rule for adding a suffix to a word ending in y), just add the suffix:


ail + -ment = ailment

assign+ -ment  = assignment

bombard + -ment = bombardment

brother +-hood = brotherhood

damp  + -ness = dampness

doubt + -ful = doubtful

defend + able = defendable

material + -ize = materialize

reach + -ing = reaching

corrupt + -ible = corruptible

tow + -ing = towing


Rule 2.  If a single syllable word ends in a short vowel sound followed by a consonant double the consonant before adding a suffix that begins with a vowel. Doubling the consonant keeps the vowel sound short:

hop + -ing = hopping              run + -er = runner

   skip + -ed = skipped              wrap + -er = wrapper



Rule 3.  For most words with more than one syllable that end with a single ‘l’ , double the ‘l’ before adding a suffix:


control + -ed = controlled          fulfil + -ment =fulfillment

propel + -er = propeller         compel + -ing = compelling



Rule 4. ‘y’ to ‘i’rule.

When you add a suffix to a word that ends in a consonant + y, change the ‘y’ to an ‘i’ before adding the suffix.

You can find quite a few examples in my week 3 blog.


Exception to this rule:

Keep the ‘y’ if you are adding the suffix –ing to a word that ends in ‘y’(to avoid having two ‘i’s’).


aerify+ -ing = aerifying                    decay + -ing = decaying

purify + -ing = purifying             qualify + -ing =qualifying


Rule 5. Silent ‘e’ rule

1. When adding a suffix that begins with a vowel or a ‘y’ to a word which ends in a silent –e, you usually drop the –e before adding the suffix:

hike + -ing = hiking                 placate + -ory =placatory

imagine + -ary = imaginary       noise + -y = noisy



An exception to the silent –e rule:

In most words that end in –ce or –ge, keep the end

–e when adding a suffix that begins with ‘a’ or ‘o’. This keeps the sound of ‘c’ and ‘g’ soft (\s\ or \j\).


deforce + -or = deforceor

embrace + -or = embraceor

outrage + -ous = outrageous

peace + -able = peaceable

salvage + -able = salvageable

venge + -ance = vengeance

   Note that in deforceor and embraceor, the –eor is actually a French suffix that has been retained in




2. You do not drop the –e if adding a suffix that begins with a consonant:

excite + -ment = excitement                  hate + -ful = hateful

supreme + -ness = supremeness



Some exceptions to 2.  are:

a few words ending in –ue to which the suffix –ly has been added: duly,truly,unduly, untruly BUT bluely.

Also, wholly(this word has a variant wholley).

Words ending in dge + -ment :

e.g. acknowledgment, dislodgment, judgment.

      However, in Merriam Webster’s Third New International Dictionary, words ending in –dge have variant spellings that retain the –e.



Rule 6.

1) When adding a suffix that begins with a vowel to a word that has more than one syllable, ends in a consonant, and has the stress on the last syllable; double the last consonant.


abhor + -ent = abhorrent (the stress is on ‘hor)       

begin + -ing = beginning (the stress is on ‘gin)

defer + -al = deferral (the stress is on ‘fer)


Some exceptions are allowance, allowable,

foreknowable, renewable, and reviewable.

      You will notice that they end in w. It is interesting to note the the combination ‘ww’ mainly occurs in compound words.


2) Do not double the last consonant for a word that has more than one syllable when the stress on the last syllable is not or does not remain on the last syllable when adding a suffix that begins with a vowel.

refer + -ence = reference (the stress on ‘fer shifts to ‘re when you add the suffix –ence).  

confer + -ence = conference (the stress on ‘fer shifts to ‘con when you add the suffix –ence)

offer + -ing = offering (the stress is not on fer)  

suffer + -ance = sufferance (the stress is not on fer)



Well, that’s all for this week. Continue working on Spell It and maintaining a list of the words that trip you up.