Spelling rules

Some spelling rules are worth learning; others are too complicated or have too many exceptions. Instead of learning all the rules, focus on learning rules which address your particular spelling problems. Following is some helpful information on the rules for building new words:

Spelling checkers will be quite helpful when you need to apply rules to word building. However, the rules for American spelling differ from those for Australian spelling. You can set your computer to English (Australia). Ideally, use a good Australian dictionary to check for words that use American spelling. Choose Australian standards and be consistent.

Words for discussing spelling

  • vowela, e, i, o and u are vowels
  • consonant: the other 21 letters of the alphabet
  • prefix: an element added to the front of a word (e.g. un/in=not, pre=before, anti=against)
  • suffix: an element added to the end of a word (e.g. –ing, –able, –ed, –ly, –ful, –ment, –tion)
  • syllable: a word or section of a word with a single sound (e.g. read, fa_mous, dif_fi_cult)
  • stress: the emphasis given to a syllable (e.g. famous, focus, occur, infer – stressed syllables are underlined)

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General rules for seven common spelling situations

In each case, note the exceptions identified for the general rules. Such exceptions are irregular spellings which do not conform to the general rules, and which must be memorised.

Situation: ie or ei?

General rules Examples
1. Write i before e, except after c.
  • achieve, believe, friend
  • receive, receipt, perceive
2. Write ie after c for words with a shen sound. ancient, efficient, sufficient, conscience
3. Write ei when the vowels sound like an a as in weigh. neighbour, vein, reign, rein, deign

Exceptions: counterfeit, either, neither, height, leisure, forfeit, foreign, science, species, seize, weird

Situation: Pluralise by adding -s or -es

General rules Examples
1. Add -es if a word ends in –ch, –sh, –ss, –x or –z.
  • arch > arches
  • clash > clashes
  • class > classes
  • box > boxes
  • quiz > quizzes
2. Add -es for most words ending in –o.
  • tomato > tomatoes
  • hero > heroes
  • go > goes
  • do > does
  • echo > echoes

Exceptions: altos, duos, pianos, radios, solos, sopranos, studios, videos, typos

Situation: Words ending in –y: when to change -y to i

General rules Examples
1. If the –y is preceded by a vowel, retain the y when adding s or a suffix.
  • convey > conveys
  • employ > employer
2. Retain the y when adding -ing.
  • try > trying
  • justify > justifying
  • certify > certifying
  • study > studying
3. If the –y is preceded by a consonant, change the y to i before adding any other suffix.
  • try > tried
  • justify > justifies
  • certify > certifiable
  • mystify > mystified
  • laboratory > laboratories

Exceptions: dryness, shyness

Situation: Words ending in –e: when to drop the -e

General rules Examples
1. Drop the –e when the suffix starts with a vowel. use > usable
2. Drop the –e when the word ends in -dge. judge > judgment
3. Drop the –e when adding -ing.
  • save > saving
  • manage > managing
  • trace > tracing
  • emerge > emerging

Exceptions: Do not drop the –e if the word ends in -ce or -ge (e.g. trace > traceable; manage > manageable)

Situation: Verbs ending in –t: when to double the –t if adding -ing, -ed and some suffixes

General rules Examples
1. Double the t for verbs of one syllable with a single vowel, or a short vowel sound.
  • rot > rotting, rotted, rotten
  • fit > fitting, fitted
  • knot > knotting, knotted
2. Double the t for verbs of more than one syllable when the stress is on the last syllable.
  • abet > abetting, abetted
  • allot > allotting, allotted
  • commit > committing, committed
  • emit > emitting, emitted
  • forget > forgetting, forgotten (but forgetful)

Exceptions: Do not double the t for verbs of one syllable with a double vowel or a long vowel sound. e.g.:

  • treat > treating, treated
  • greet > greeting, greeted

Situation: Verbs ending in –r: when to double the –r if adding -ing, -ed and some suffixes

General rules Examples Exceptions
1. Double the r for verbs of one syllable when the final r is preceded by a single vowel.
  • star > starring, starred, starry
  • tar > tarring, tarred
  • war > warring, warred (but warfare)
  • scar > scarring, scarred
  • stir > stirring, stirred
Do not double the r for verbs of one syllable when the final r is preceded by two vowels (e.g. fear > fearing, feared)
2. Double the r for words of more than one syllable when the stress does not fall on the first syllable.
  • concur > concurring, concurred, concurrence
  • occur > occurring, occurred, occurrence
  • defer > deferring, deferred (but deference)
  • deter > deterring, deterred, deterrence
  • infer > inferring, inferred (but inference)
  • prefer > preferring, preferred (but preference)
  • refer > referring, referred (but reference)
Do not double the r for words of more than one syllable, when the stress falls on the first syllable (e.g. prosper > prospering, prospered)

Situation: Verbs ending in l: when to double the –l if adding -ing, -ed and some suffixes

General rule Examples Exceptions
Double the l when it is preceded by a single vowel.
  • cancel > cancelling, cancelled, cancellation
  • enrol > enrolling, enrolled (but enrolment)
  • fulfil > fulfilling, fulfilled, fulfillment
  • level > levelling, levelled
  • travel > travelling, travelled, traveller
Do not double the l when it is preceded by two vowels (e.g. conceal > concealing, concealed)

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Three types of irregular spelling

There are no reliable rules covering the following situations and words, so they simply have to be memorised.

Dropping letters

Many words drop a letter when adding a suffix, but it is not always the final letter.

  • argue > argument
  • proceed > procedure
  • humour > humorous
  • disaster > disastrous
  • repeat > repetition
  • administer > administration
Word endings such as -able/-ible, -ant/-ance; -ent/-ence
  • admirable, preventable, suitable, dependable
  • negligible, incredible, invisible, sensible
  • attendance, ignorance, nuisance, importance
  • sentence, difference, independence, intelligence
Silent letters

Some words include letters which are not pronounced when the word is spoken.

debt, doubt, subtle, advertisement, campaign, design, ghetto, heir, rhythm, knife, knowledge, column, solemnpneumatic, island, mortgage, often, gauge

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Rules for Australian and American spelling

There are often considerable differences between Australian and American spelling. You should use Australian spelling in preference to American spelling, but if American spelling is considered acceptable, then make sure you use it consistently in your academic writing.

-re/-er: Australian spelling uses -re
theatre, litre, centre, calibre, sombre, fibre—not theater, liter, center, etc.
-our/-or: Australian spelling uses -our
colour, honour, neighbour—not color, honor, neighbor
ise/-ize: both are acceptable, but the Australian preference is for -ise
criticise rather than criticize
Verbs ending in -se: Australian spelling requires -se for the verb and -ce for the noun forms
Other common words
  • aeroplane—not airplane
  • traveller—not traveler
  • defence—not defense

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