Style Guide > 4 Language > [4.38] Spelling
[4.38] Spelling
4.38 Use the main listing and ignore alternative spellings
The Oxford English Dictionary is your sole guide to spelling. If more than one spelling is permitted, use only the preferred spelling, which is the main listing and shown first in each entry:
Note that words ending with -ize, such as normalize and summarize, are the preferred English spellings, and not Americanisms. The -ise spellings are allowed (preferred only for exclusively Australian audiences) but should be avoided when writing for international audiences. The rules for -ize and -ise, doubling consonants when forming participles, and other spelling rules, are listed in the Spelling rules topic.
[4.39] Spelling rules
4.39 Spelling rules
The most common word constructions are listed here, showing their spellings in the English language variants of International (Oxford, British), Australian, Canadian, and US. Examples of some derivative words are also provided. The lists of examples provided are not comprehensive and are only intended to demonstrate the rule.
Spelling patterns
One or two l’s?
Doubling the final consonant
Adding -ed and -ing
Adding -able, -ability, -ably, -ableness
Adding -ment, -mental, -mentally
Adding -ly
Adding other suffixes
4.40 Spelling patterns
Common differences in spelling patterns between International (Oxford, British), Australian, Canadian, and US English include:
-ize, -ise
-our, -or
-re, -er
-ce, -se
-yse, -yze
-ogue, -og
-amme, -am
-ward, -wards
-ae-/-oe-, -e-
-ize, -ise
The suffix -ize can be added to certain nouns and adjectives (the stem) to form a verb meaning to make, become, treat as, or follow the practice of the stem. For example, initialize is derived from the stem initial (n., adj.)—that is, to make initial or to return to an initial state. The participles (and adjective and gerund) follow the spelling of the infinitive: initialize (v., inf.), initializing (pres. part., ger.), and initialized (past part., adj.).
Many verbs (not just the ones ending with -ize) can be nominalized (to make nominal—that is, to make into a noun). The -ize verbs are usually nominalized by dropping the final -e and adding -ation. Hence, initial (adj.) is the stem, initialize is its verb and initialization is its nominalization. For more information, see Nominalizations. Also note that the gerund initializing is also a noun.
Although mistakenly thought by some to be an Americanism, the -ize spelling has always been preferred by the Oxford Dictionary (International English). Oxford quaintly describes the -ise spelling as being “a bit too French” for their liking.
There are, however, some words that are always spelled with -ise, regardless of which dictionary you follow (see “exceptions” in table below). Specifically, use -ise when it is part of a larger stem, such as pro-mise, sur-prise and de-vise, or when the corresponding noun is always spelled with -ise, such as advertise (advertisement) and televise (television).
Otherwise the verb and its nominalization follow the same rule, for example, rationalize-rationalization. The following table contains just a few examples—there are many more.
 
-our, -or
Color (colour) is one of the most prevalent Americanisms, but there are exceptions that are spelled either -or or -our in all dictionaries. The following table contains just a few examples—there are many more.
 
glamour, glamor
coloration, colorize, contour, honorary, humorous, invigorate, laborious
-re, -er
These differences are most common with words ending -tre and -bre. However, the -er spelling is not uniformly applied in the US. In particular, both theatre and centre are common. And although common, Americanized spellings of SI units (meter and liter) should be avoided, even when writing for an American audience (ISO standards take precedence).
 
caliber, calibrate
center/centre, central
fiber, fibrous
liter (use litre)
luster, lustrous
meter, meter (use metre)
theater/theatre, theatrics, theatrical
titer, titrate
-ce, -se
The -ce/-se noun-verb relationship is generally common to all English variants (including US), as in advice (n.) and advise (v.). The only exceptions are US where the noun is spelled with an s. Note that the verb and its derivations take the s in all dictionaries (defensive, offensive, pretension, advisory, devisive).
 
-yse, -yze
Note that the corresponding nominalizations of words ending with -yse/-yze are spelled with an s in all dictionaries (analysis, paralysis).
 
-ogue, -og
Although the -og spelling is usual, the -ogue spelling is also common in the US—especially dialogue.
 
analog, analogue
-amme, -am
The Oxford spells (computer) program with one m and all other programmes with two (work, TV, exploration, etc.). In all other dictionaries (Australian, Canadian, American), both are spelled program. Diagram and diagrammatically, however, are spelled the same in all dictionaries.
-ward, -wards
The adjective forward (a forward move) is spelled without an s in all dictionaries. And the adverb forwards (to move forwards) takes the s, except in the US. The same rule applies to all -ward words (upward, backward, etc.), although the adjective toward is uncommon. Also see forwards vs forward for usage in common phrases, such as forward-looking and to look forward to.
-ae-/-oe-, -e-
Words spelled with -ae- and -oe- are often medical, but there are numerous examples in common usage, such as aeroplane and manoevre.
 
4.41 One or two l’s?
Words spelled with one or two l’s are frequently misspelled because of differences with US English. For example, calliper, jewellery, and enrol (Int., Aus., Can.) and caliper, jewelry, and enroll (US). There are also specific rules that govern Doubling the l (model-modelled) and Dropping the l (install-instalment) when adding endings to words ending with an l. These rules are also a major difference between US and the other forms of English.
Words spelled with one or two l’s
Some common differences are shown below. Note that in some cases the US spelling is one l and in others it’s two.
 
Doubling the l
In International, Australian and Canadian English, the l is a special case: when adding endings that begin with a vowel to words ending in a vowel plus l, double the l (e.g. travelled, crueller).
However, in US English, doubling the l follows the universal rule of Ending with a consonant preceded by a vowel—that is, the l is treated the same as all other consonants.
 
Dropping the l
When adding suffixes that begin with a consonant to words that end in a double l, drop the final l—for example, skill-skilful and install-instalment. In US English the final l is kept (skillful, installment).
 
Note that words ending with one l (annul, fulfil) are unchanged (annulment, fulfilment).
4.42 Doubling the final consonant
Note. In non-US English, words ending with l obey different rules (Doubling the l, Dropping the l).
Note. These rules are common to all English variants.
Ending with a consonant preceded by a vowel
When adding a suffix beginning with a vowel (-ed, -ing, -able, -ion) to verbs ending with a consonant preceded by a vowel, double the final consonant if the last syllable is stressed or the word is one syllable with a short vowel.
Ending with a double consonant
If the word ends with a double consonant, don’t drop the final consonant (embarrass-embarassing-embarassment).
 
One syllable (short vowel): capped, fitting, dubbed
More than one syllable (final syllable stressed): omitted, occurring, admitted, formatting, regrettable, unforgettable
One syllable (long vowel): drawing, nailed, keeping
More than one syllable (final syllable unstressed): biased, bulleted, interpreted, marketing, budgeted, focused, profited, benefited, developing
4.43 Adding -ed and -ing
Note. This rule is common to all English variants.
Ending with -e
If a verb ends with e, add d to form the past tense (discouraged, waved, lodged). Most verbs drop the e before -ing (timing, using, engaging). This rule is common to all English variants. Also see Adding -able, -ability, -ably, -ableness and Adding -ment, -mental, -mentally.
 
4.44 Adding -able, -ability, -ably, -ableness
Note. This rule is common to all English variants, with exceptions.
Ending with -e
In general, with the exception of verbs ending with -ce or -ge (see below), drop the final e: breathable, cavability (mining), curable, minable, movable, notably, provable, quotable, scalable, solvable, usable, usability, believable, believability, believably, decidable. However, there are exceptions that retain the e (non-US variants only).
 
Ending with -ce, -ge, or -dge
Keep the final e to maintain the soft sound: bridgeable, pronounceable, changeable, changeably, changeability, changeableness, interchangeable, traceable, traceability, knowledgeable.
 
Ending with -y
For words ending in -y as a final syllable, change the y to i: undeniable, reliable.
Doubled in participle
For words that double the final consonant in past participle form, double the consonant before the suffix: biddable, forgettable, programmable.
 
4.45 Adding -ment, -mental, -mentally
Note. This rule is common to all English variants, with US exceptions.
Ending with -e
Keep the final -e: abatement, easement, basement, ensnarement.
Ending with -ce, -ge, or -dge
Keep the final e to maintain the soft sound: acknowledgement, judgement, lodgement, management, enhancement, discouragement, replacement, inducement. In US English, the e is usually dropped when adding -ment to words ending with -dge.
 
acknowledgment, judgment, lodgment
4.46 Adding -ly
Note. This rule is common to all English variants, with US exceptions.
Ending with -e
Keep the final e to when adding -ly to words ending with e (astutely, finely, vaguely).
 
4.47 Adding other suffixes
Refer to Adding -ed and -ing, Adding -able, -ability, -ably, -ableness, Adding -ment, -mental, -mentally, and Adding -ly for those specific suffixes. For other suffixes, follow these general rules.
Ending with -y
In general, change the y to i when the -y is pronounced as a final syllable (readiness) except when forming a closed compound—that is, when a common phrase is turned into a single word (handyman).
Ending with -e
In general, keep the final e when the suffix begins with a consonant (wholesome, hopeful). Drop the e when the suffix begins with a vowel (distribution, determination).
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